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ohwgiles_laminar/UserManual.md
Oliver Giles 212cfaf8ab UserManual: laminard env vars with docker 
explain how laminard uses environment variables and
recommend how to set them when using docker

resolves #136
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Introduction

Laminar is a lightweight and modular Continuous Integration service for Linux. It is self-hosted and developer-friendly, eschewing a configuration web UI in favor of simple version-controllable configuration files and scripts.

Laminar encourages the use of existing GNU/Linux tools such as bash and cron instead of reinventing them.

Although the status and progress front-end is very user-friendly, administering a Laminar instance requires writing shell scripts and manually editing configuration files. That being said, there is nothing esoteric here and the tutorial below should be straightforward for anyone with even very basic Linux server administration experience.

Throughout this document, the fixed base path /var/lib/laminar is used. This is the default path and can be changed by setting LAMINAR_HOME in /etc/laminar.conf as desired.

Terminology

  • job: a task, identified by a name, comprising of one or more executable scripts.
  • run: a numbered execution of a job

Installing Laminar

Pre-built packages are available for Debian 9 (Stretch) and CentOS 7 on x86_64. Alternatively, Laminar may be built from source for any Linux distribution.

Installation from binaries

Alternatively to the source-based approach shown above, precompiled packages are supplied for x86_64 Debian 9 (Stretch) and CentOS 7

Under Debian:

wget https://github.com/ohwgiles/laminar/releases/download/0.6/laminar-0.6-1-amd64.deb
sudo apt install laminar-0.6-1-amd64.deb

Under CentOS:

wget https://github.com/ohwgiles/laminar/releases/download/0.5/laminar-0.6-1.x86_64.rpm
sudo yum install laminar-0.6-1.x86_64.rpm

Both install packages will create a new laminar user and install (but not activate) a systemd service for launching the laminar daemon.

Building from source

See the development README for instructions for installing from source.

Building for Docker

You can build an image that runs laminard by default, and contains laminarc for use based on alpine:edge using the Dockerfile in the docker/ directory.

# from the repository root:
docker build [-t image:tag] -f docker/Dockerfile .

Keep in mind that this is meant to be used as a base image to build from, so it contains only the minimum packages required to run laminar. The only shell available by default is sh (so scripts with #!/bin/bash will fail to execute) and it does not have ssh or git. You can use this image to run a basic build server, but it is recommended that you build a custom image from this base to better suit your needs.

The container will execute laminard by default. To start a laminar server with docker you can simply run the image as a daemon, for example:

docker run -d --name laminar_server -p 8080:8080 -v path/to/laminardir:/var/lib/laminar --env-file path/to/laminar.conf laminar:latest

The -v flag is necessary to persist job scripts and artefacts beyond the container lifetime.

The --env-file flag is necessary to pass configuration from laminar.conf to laminard because laminard does not read /etc/laminar.conf directly but expects variables within to be exported by systemd or other process supervisor.

Executing laminarc may be done in any of the usual ways, for example:

docker exec -i laminar_server laminarc queue example_task

Alternatively, you might use an external laminarc.

Service configuration

Use systemctl start laminar to start the laminar system service and systemctl enable laminar to launch it automatically on system boot.

After starting the service, an empty laminar dashboard should be available at http://localhost:8080

Laminar's configuration file may be found at /etc/laminar.conf. Laminar will start with reasonable defaults if no configuration can be found.

Running on a different HTTP port or Unix socket

Edit /etc/laminar.conf and change LAMINAR_BIND_HTTP to IPADDR:PORT, unix:PATH/TO/SOCKET or unix-abstract:SOCKETNAME. IPADDR may be * to bind on all interfaces. The default is *:8080.

Do not attempt to run laminar on port 80. This requires running as root, and Laminar will not drop privileges when executing job scripts! For a more complete integrated solution (including SSL), run laminar as a reverse proxy behind a regular webserver.

Running behind a reverse proxy

A reverse proxy is required if you want Laminar to share a port with other web services. It is also recommended to improve performance by serving artefacts directly or providing a caching layer for static assets.

If you use artefacts, note that Laminar is not designed as a file server, and better performance will be achieved by allowing the frontend web server to serve the archive directory directly (e.g. using a Location directive).

Laminar uses Sever Sent Events to provide a responsive, auto-updating display without polling. Most frontend webservers should handle this without any extra configuration.

If you use a reverse proxy to host Laminar at a subfolder instead of a subdomain root, the <base href> needs to be updated to ensure all links point to their proper targets. This can be done by setting LAMINAR_BASE_URL in /etc/laminar.conf.

More configuration options

See the reference section

Defining a job

To create a job that downloads and compiles GNU Hello, create the file /var/lib/laminar/cfg/jobs/hello.run with the following content:

#!/bin/bash -ex
wget ftp://ftp.gnu.org/gnu/hello/hello-2.10.tar.gz
tar xzf hello-2.10.tar.gz
cd hello-2.10
./configure
make

Laminar uses your script's exit code to determine whether to mark the run as successful or failed. If your script is written in bash, the -e option is helpful for this. See also Exit and Exit Status.

Don't forget to mark the script executable:

chmod +x /var/lib/laminar/cfg/jobs/hello.run

Triggering a run

To queue execution of the hello job, run

laminarc queue hello

In this case, laminarc returns immediately, with its error code indicating whether adding the job to the queue was sucessful. The run number will be printed to standard output.

If the server is busy, a run may wait in the queue for some time. To have laminarc instead block until the run leaves the queue and starts executing, use

laminarc start hello

In this case, laminarc blocks until the job starts executing, or returns immediately if queueing failed. The run number will be printed to standard output.

Finally, to launch and run the hello job to completion, execute

laminarc run hello

In this case, laminarc's return value indicates whether the run completed successfully.

In all cases, a started run means the /var/lib/laminar/cfg/jobs/hello.run script will be executed, with a working directory of /var/lib/laminar/run/hello/1 (or current run number)

The result and log output should be visible in the Web UI at http://localhost:8080/jobs/hello/1

Also note that all the above commands can simultaneously trigger multiple different jobs:

laminarc queue test-host test-target

Isn't there a "Build Now" button I can click?

This is against the design principles of Laminar and was deliberately excluded. Laminar's web UI is strictly read-only, making it simple to deploy in mixed-permission or public environments without an authentication layer. Furthermore, Laminar tries to encourage ideal continuous integration, where manual triggering is an anti-pattern. Want to make a release? Push a git tag and implement a post-receive hook. Want to re-run a build due to sporadic failure/flaky tests? Fix the tests locally and push a patch. Experience shows that a manual trigger such as a "Build Now" button is often used as a crutch to avoid doing the correct thing, negatively impacting traceability and quality.

Listing jobs from the command line

laminarc may be used to inspect the server state:

  • laminarc show-jobs: Lists all files matching /var/lib/laminar/cfg/jobs/*.run on the server side.
  • laminarc show-running: Lists all currently running jobs and their run numbers.
  • laminarc show-queued: Lists all jobs waiting in the queue.

Triggering a job at a certain time

This is what cron is for. To trigger a build of hello every day at 0300, add

0 3 * * * LAMINAR_REASON="Nightly build" laminarc queue hello

to laminar's crontab. For more information about cron, see man crontab.

LAMINAR_REASON is an optional human-readable string that will be displayed in the web UI as the cause of the build.

Triggering on a git commit

This is what git hooks are for. To create a hook that triggers the example-build job when a push is made to the example repository, create the file hooks/post-receive in the example.git bare repository.

#!/bin/bash
LAMINAR_REASON="Push to git repository" laminarc queue example-build

What if your git server is not the same machine as the laminar instance?

Triggering on a remote laminar instance

laminarc and laminard communicate by default over an abstract unix socket. This means that any user on the same machine can send commands to the laminar service.

On a trusted network, you might want laminard to listen for commands on a TCP port instead. To achieve this, in /etc/laminar.conf, set

LAMINAR_BIND_RPC=*:9997

or any interface/port combination you like. This option uses the same syntax as LAMINAR_BIND_HTTP.

Then, point laminarc to the new location using an environment variable:

LAMINAR_HOST=192.168.1.1:9997 laminarc queue example

If you need more flexibility, consider running the communication channel as a regular unix socket and applying user and group permissions to the file. To achieve this, set

LAMINAR_BIND_RPC=unix:/var/run/laminar.sock

or similar path in /etc/laminar.conf.

This can be securely and flexibly combined with remote triggering using ssh. There is no need to allow the client full shell access to the server machine, the ssh server can restrict certain users to certain commands (in this case laminarc). See the authorized_keys section of the sshd man page for further information.

Triggering on a push to GitHub

Consider using webhook or a similar application to call laminarc.

Viewing job logs

A job's console output can be viewed on the Web UI at http://localhost:8080/jobs/$NAME/$NUMBER.

Additionally, the raw log output may be fetched over a plain HTTP request to http://localhost:8080/log/$NAME/$NUMBER. The response will be chunked, allowing this mechanism to also be used for in-progress jobs. Furthermore, the special endpoint http://localhost:8080/log/$NAME/latest will redirect to the most recent log output. Be aware that the use of this endpoint may be subject to races when new jobs start.

Job chains

A typical pipeline may involve several steps, such as build, test and deploy. Depending on the project, these may be broken up into seperate laminar jobs for maximal flexibility.

The preferred way to accomplish this in Laminar is to use the same method as regular run triggering, that is, calling laminarc directly in your example.run scripts.

#!/bin/bash -xe

# simultaneously starts example-test-qemu and example-test-target
# and returns a non-zero error code if either of them fail
laminarc run example-test-qemu example-test-target

An advantage to using this laminarc approach from bash or other scripting language is that it enables highly dynamic pipelines, since you can execute commands like

if [ ... ]; then
  laminarc run example-downstream-special
else
  laminarc run example-downstream-regular
fi

laminarc run example-test-$TARGET_PLATFORM

laminarc reads the $JOB and $RUN variables set by laminard and passes them as part of the queue/start/run request so the dependency chain can always be traced back.

Parameterized runs

Any argument passed to laminarc of the form var=value will be exposed as an environment variable in the corresponding build scripts. For example:

laminarc queue example foo=bar

In /var/lib/laminar/cfg/jobs/example.run:

#!/bin/bash
if [ "$foo" == "bar" ]; then
   ...
else
   ...
fi

Pre- and post-build actions

If the script /var/lib/laminar/cfg/jobs/example.before exists, it will be executed as part of the example job, before the primary /var/lib/laminar/cfg/jobs/example.run script.

Similarly, if the script /var/lib/laminar/cfg/jobs/example.after script exists, it will be executed as part of the example job, after the primary var/lib/laminar/cfg/jobs/example.run script. In this script, the $RESULT variable will be success, failed, or aborted according to the result of example.run.

See also script execution order

Conditionally trigger a downstream job

Often, you may wish to only trigger the example-test job if the example-build job completed successfully. example-build.after might look like this:

#!/bin/bash -xe
if [ "$RESULT" == "success" ]; then
  laminarc queue example-test
fi

Passing data between scripts

Any script can set environment variables that will stay exposed for subsequent scripts of the same run using laminarc set. In example.before:

#!/bin/bash
laminarc set foo=bar

Then in example.run

#!/bin/bash
echo $foo            # prints "bar"

Archiving artefacts

Laminar's default behaviour is to remove the run directory /var/lib/laminar/run/JOB/RUN after its completion. This prevents the typical CI disk usage explosion and encourages the user to judiciously select artefacts for archive.

Laminar provides an archive directory /var/lib/laminar/archive/JOB/RUN and exposes its path in $ARCHIVE. example-build.after might look like this:

#!/bin/bash -xe
cp example.out $ARCHIVE/

This folder structure has been chosen to make it easy for system administrators to host the archive on a separate partition or network drive.

Accessing artefacts from an upstream build

Rather than implementing a separate mechanism for this, the path of the upstream's archive should be passed to the downstream run as a parameter. See Parameterized runs.

Email and IM Notifications

As well as per-job .after scripts, a common use case is to send a notification for every job completion. If the global after script at /var/lib/laminar/cfg/after exists, it will be executed after every job. One way to use this might be:

#!/bin/bash -xe
if [ "$RESULT" != "$LAST_RESULT" ]; then
  sendmail -t <<EOF
To: engineering@company.com
Subject: Laminar $JOB #$RUN: $RESULT
From: laminar-ci@company.com

Laminar $JOB #$RUN: $RESULT
EOF
fi

Of course, you can make this as pretty as you like. A helper script can be a good choice here.

If you want to send to different addresses dependending on the job, replace engineering@company.com above with a variable, e.g. $RECIPIENTS, and set RECIPIENTS=nora@company.com,joe@company.com in /var/lib/laminar/cfg/jobs/JOB.env. See Environment variables.

You could also update the $RECIPIENTS variable dynamically based on the build itself. For example, if your run script accepts a parameter $rev which is a git commit id, as part of your job's .after script you could do the following:

author_email=$(git show -s --format='%ae' $rev)
laminarc set RECIPIENTS $author_email

See notify-email-pretty.sh and notify-email-text-log.sh.

Helper scripts

The directory /var/lib/laminar/cfg/scripts is automatically prepended to the PATH of all runs. It is a convenient place to drop executables or scripts to help keep individual job scripts clean and concise. A simple example might be /var/lib/laminar/cfg/scripts/success_trigger:

#!/bin/bash -e
if [ "$RESULT" == "success" ]; then
  laminarc queue "$@"
fi

With this in place, any .after script can conditionally trigger a downstream job more succinctly:

success_trigger example-test

Another excellent candidate for helper scripts is automatically sending notifications on job status change.

Data sharing and Workspaces

Often, a job will require a (relatively) large block of (relatively) unchanging data. Examples are a git repository with a long history, or static asset files. Instead of fetching everything from scratch for every run, a job may make use a workspace, a per-job folder that is reused between builds.

For example, the following script creates a tarball containing both compiled output and some static asset files from the workspace:

#!/bin/bash -ex
git clone /path/to/sources .
make
# Use a hardlink so the arguments to tar will be relative to the CWD
ln $WORKSPACE/StaticAsset.bin ./
tar zc a.out StaticAsset.bin > MyProject.tar.gz
# Archive the artefact (consider moving this to the .after script)
mv MyProject.tar.gz $ARCHIVE/

For a project with a large git history, it can be more efficient to store the sources in the workspace:

#!/bin/bash -ex
cd $WORKSPACE/myproject
git pull
cd -

cmake $WORKSPACE/myproject
make -j4

Laminar will automatically create the workspace for a job if it doesn't exist when a job is executed. In this case, the /var/lib/laminar/cfg/jobs/JOBNAME.init will be executed if it exists. This is an excellent place to prepare the workspace to a state where subsequent builds can rely on its content:

#!/bin/bash -e
echo Initializing workspace
git clone git@example.com:company/project.git .

CAUTION: By default, laminar permits multiple simultaneous runs of the same job. If a job can modify the workspace, this might result in inconsistent builds when simultaneous runs access the same content. This is unlikely to be an issue for nightly builds, but for SCM-triggered builds it will be. To solve this, use contexts to restrict simultaneous execution of jobs, or consider flock.

The following example uses flock to efficiently share a git repository workspace between multiple simultaneous builds:

#!/bin/bash -xe

# This script expects to be passed the parameter 'rev' which
# should refer to a specific git commit in its source repository.
# The commit ids could have been read from a server-side
# post-commit git hook, where many commits could have been pushed
# at once, but we want to check them all individually. This means
# this job can be executed several times (with different values
# for $rev) simultaneously.

# Locked subshell for modifying the workspace
(
  flock 200
  cd $WORKSPACE
  # Download all the latest commits
  git fetch
  git checkout $rev
  cd -
  # Fast copy (hard-link) the source from the specific checkout
  # to the build dir. This relies on the fact that git unlinks
  # during checkout, effectively implementing copy-on-write.
  cp -al $WORKSPACE/src src
) 200>$WORKSPACE

# run the (much longer) regular build process
make -C src

Aborting running jobs

After a timeout

To configure a maximum execution time in seconds for a job, add a line to /var/lib/laminar/cfg/jobs/JOBNAME.conf:

TIMEOUT=120

Manually

laminarc abort $JOBNAME $NUMBER

Contexts

In Laminar, each run of a job is associated with a context. The context defines an integer number of executors, which is the amount of runs which the context will accept simultaneously. A context may also provide additional environment variables.

Uses for this feature include limiting the amount of concurrent CPU-intensive jobs (such as compilation); and controlling access to jobs executed remotely.

If no contexts are defined, Laminar will behave as if there is a single context named "default", with 6 executors. This is a reasonable default that allows simple setups to work without any consideration of contexts.

Defining a context

To create a context named "my-env" which only allows a single run at once, create /var/lib/laminar/cfg/contexts/my-env.conf with the content:

EXECUTORS=1

Associating a job with a context

When trying to start a job, laminar will wait until the job can be matched to a context which has at least one free executor. There are two ways to associate jobs and contexts. You can specify a comma-separated list of patterns JOBS in the context configuration file /var/lib/laminar/cfg/contexts/CONTEXT.conf:

JOBS=amd64-target-*,usage-monitor

This approach is often preferred when you have many jobs that need to share limited resources.

Alternatively, you can set

CONTEXTS=my-env-*,special_context

in /var/lib/laminar/cfg/jobs/JOB.conf. This approach is often preferred when you have a small number of jobs that require exclusive access to an environment and you can supply alternative environments (e.g. target devices), because new contexts can be added without modifying the job configuration.

In both cases, Laminar will iterate over the known contexts and associate the run with the first matching context with free executors. Patterns are glob expressions.

If CONTEXTS is empty or absent (or if JOB.conf doesn't exist), laminar will behave as if CONTEXTS=default were defined.

Adding environment to a context

Append desired environment variables to /var/lib/laminar/cfg/contexts/CONTEXT_NAME.conf:

DUT_IP=192.168.3.2
FOO=bar

This environment will then be available the run script of jobs associated with this context. Note that these definitions are not expanded by a shell, so FOO="bar" would result in a variable FOO whose contents include double-quotes.

Remote jobs

Laminar provides no specific support, bash, ssh and possibly NFS are all you need. For example, consider two identical target devices on which test jobs can be run in parallel. You might create a context for each, /var/lib/laminar/cfg/contexts/target{1,2}.conf:

EXECUTORS=1

In each context's .env file, set the individual device's IP address:

TARGET_IP=192.168.0.123

And mark the job accordingly in /var/lib/laminar/cfg/jobs/myproject-test.conf:

CONTEXTS=target*

This means the job script /var/lib/laminar/cfg/jobs/myproject-test.run can be generic:

#!/bin/bash -e

ssh root@$TARGET_IP /bin/bash -xe <<"EOF"
  uname -a
  ...
EOF
scp root@$TARGET_IP:result.xml "$ARCHIVE/"

Don't forget to add the laminar user's public ssh key to the remote's authorized_keys.

Docker container jobs

Laminar provides no specific support, but just like remote jobs these are easily implementable in plain bash:

#!/bin/bash

docker run --rm -ti -v $PWD:/root ubuntu /bin/bash -xe <<EOF
  git clone http://...
  ...
EOF

Colours in log output

Laminar's frontend supports ANSI colours using the ansi-up library. Unfortunately, there is no standard way of convincing applications to output colours when not connected to a tty. It is recommended to set CLICOLOR_FORCE=1 in Laminar's global environment file, plus any of the following environment variables that may be relevant (please submit more):

  • git: GIT_CONFIG_PARAMETERS='color.status=always' 'color.ui=always'
  • google test: GTEST_COLOR=1
  • grep: GREP_OPTIONS=--color=always

More intrusive options for other common tools which do not support enabling colours via environment variable:

  • gcc and clang: Add -fdiagnostics-color=always to compile flags

Customizing the WebUI

Organising jobs into groups

Groups may be used to organise the "Jobs" page into tabs. Edit /var/lib/laminar/cfg/groups.conf and define the matched jobs as a javascript regular expression, for example:

Builds=compile-\w+
My Fav Jobs=^(target-foo-(build|deploy)|run-benchmarks)$
All=.*

Changes to this file are detected immediately and will be visible on next page refresh.

Adding a description to a job

Edit /var/lib/laminar/cfg/jobs/$JOBNAME.conf:

DESCRIPTION=Anything here will appear on the job page in the frontend <em>unescaped</em>.

Setting the page title

Change LAMINAR_TITLE in /etc/laminar.conf to your preferred page title. Laminar must be restarted for this change to take effect.

Custom HTML template

If it exists, the file /var/lib/laminar/custom/index.html will be served by laminar instead of the default markup that is bundled into the Laminar binary. This file can be used to change any aspect of Laminar's WebUI, for example adding menu links or adding a custom stylesheet. Any required assets will need to be served directly from your HTTP reverse proxy or other HTTP server.

An example customization can be found at cweagans/semantic-laminar-theme.

Badges

Laminar will serve a job's current status as a pretty badge at the url /badge/JOBNAME.svg. This can be used as a link to your server instance from your Github README.md file or cat blog:

<a href="https://my-example-laminar-server.com/jobs/my-project">
  <img src="https://my-example-laminar-server.com/badge/my-project.svg">
</a>

Reference

Service configuration file

laminard reads the following variables from the environment, which are expected to be sourced by systemd from /etc/laminar.conf:

  • LAMINAR_HOME: The directory in which laminard should find job configuration and create run directories. Default /var/lib/laminar
  • LAMINAR_BIND_HTTP: The interface/port or unix socket on which laminard should listen for incoming connections to the web frontend. Default *:8080
  • LAMINAR_BIND_RPC: The interface/port or unix socket on which laminard should listen for incoming commands such as build triggers. Default unix-abstract:laminar
  • LAMINAR_TITLE: The page title to show in the web frontend.
  • LAMINAR_KEEP_RUNDIRS: Set to an integer defining how many rundirs to keep per job. The lowest-numbered ones will be deleted. The default is 0, meaning all run dirs will be immediately deleted.
  • LAMINAR_ARCHIVE_URL: If set, the web frontend served by laminard will use this URL to form links to artefacts archived jobs. Must be synchronized with web server configuration.

Script execution order

When $JOB is triggered, the following scripts (relative to $LAMINAR_HOME/cfg) may be executed:

  • jobs/$JOB.init if the workspace did not exist
  • before
  • jobs/$JOB.before
  • jobs/$JOB.run
  • jobs/$JOB.after
  • after

Environment variables

The following variables are available in run scripts:

  • RUN integer number of this run
  • JOB string name of this job
  • RESULT string run status: "success", "failed", etc.
  • LAST_RESULT string previous run status
  • WORKSPACE path to this job's workspace
  • ARCHIVE path to this run's archive
  • CONTEXT the context of this run

In addition, $LAMINAR_HOME/cfg/scripts is prepended to $PATH. See helper scripts.

Laminar will also export variables in the form KEY=VALUE found in these files:

  • env
  • contexts/$CONTEXT.env
  • jobs/$JOB.env

Note that definitions in these files are not expanded by a shell, so FOO="bar" would result in a variable FOO whose contents include double-quotes.

Finally, variables supplied on the command-line call to laminarc queue, laminarc start or laminarc run will be available. See parameterized runs

laminarc

laminarc commands are:

  • queue [JOB [PARAMS...]]... adds one or more jobs to the queue with optional parameters, returning immediately.
  • start [JOB [PARAMS...]]... starts one or more jobs with optional parameters, returning when the jobs begin execution.
  • run [JOB [PARAMS...]]... triggers one or more jobs with optional parameters and waits for the completion of all jobs.
  • set [VARIABLE=VALUE]... sets one or more variables to be exported in subsequent scripts for the run identified by the $JOB and $RUN environment variables
  • show-jobs shows the known jobs on the server ($LAMINAR_HOME/cfg/jobs/*.run).
  • show-running shows the currently running jobs with their numbers.
  • show-queued shows the names of the jobs waiting in the queue.
  • abort JOB NUMBER manually aborts a currently running job by name and number.

laminarc connects to laminard using the address supplied by the LAMINAR_HOST environment variable. If it is not set, laminarc will first attempt to use LAMINAR_BIND_RPC, which will be available if laminarc is executed from a script within laminard. If neither LAMINAR_HOST nor LAMINAR_BIND_RPC is set, laminarc will assume a default host of unix-abstract:laminar.

All commands return zero on success or a non-zero code if the command could not be executed. laminarc run will return a non-zero exit status if any executed job failed.