4. Integration commands

Sometimes a software requires more configuration or processing than what is performed at installation time, otherwise it will not run properly.

This is especially true in cases where a daemon or library interoperates with third party extensions and needs to maintain a system wide cache whenever its extensions are installed or removed; system wide font caches are an example of this.

In these cases we use integration commands to ensure that a runtime is ready to run after all of its components have been staged.

Note

This example is distributed with BuildStream in the doc/examples/integration-commands subdirectory.

4.1. Overview

In this chapter, we’ll be exploring integration commands, which will be our first look at public data.

4.2. Project structure

4.2.1. project.conf and elements/base.bst

The project.conf and base stack stack element are configured in the same way as in the previous chapter: Running commands.

4.2.2. elements/base/alpine.bst

kind: import
description: |

    Alpine Linux base runtime

sources:
- kind: tar
  url: alpine:integration-tests-base.v1.x86_64.tar.xz
  ref: 3eb559250ba82b64a68d86d0636a6b127aa5f6d25d3601a79f79214dc9703639

#
# Run ldconfig in the libdir before running anything
#
public:
  bst:
    integration-commands:
    - ldconfig "%{libdir}"

This is the same base/alpine.bst we’ve seen in previous chapters, except that we’ve added an integration command.

This informs BuildStream that whenever the output of this element is expected to run, this command should be run first. In this case we are simply running ldconfig as a precautionary measure, to ensure that the runtime linker is ready to find any shared libraries we may have added to %{libdir}.

4.2.2.1. Looking at public data

The integration commands used here is the first time we’ve used any builtin public data.

Public data is a free form portion of an element’s configuration and is not necessarily understood by the element on which it is declared, public data is intended to be read by its reverse dependency elements.

This allows annotations on some elements to inform elements later in the dependency chain about details of its artifact, or to suggest how it should be processed.

4.2.3. elements/libhello.bst and elements/hello.bst

These are basically manual elements very similar to the ones we’ve seen in the previous chapter: Running commands.

These produce a library and a hello program which uses the library, we will consider these irrelevant to the topic and leave examination of their sources as an exercise for the reader.

4.3. Using the project

4.3.1. Build the hello.bst element

To build the project, run bst build in the following way:

user@host:~/integration-commands$ bst build hello.bst

[--:--:--][        ][    main:core activity                 ] START   Build
[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Resolving cached state
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving cached state
[--:--:--][        ][    main:core activity                 ] START   Checking sources
[00:00:00][        ][    main:core activity                 ] SUCCESS Checking sources

BuildStream Version 1.93.5
    Session Start: Wednesday, 19-08-2020 at 14:56:23
    Project:       integration-commands (/home/user/integration-commands)
    Targets:       hello.bst

User Configuration
    Configuration File:      /home/user/.config/buildstream.conf
    Cache Directory:         /home/user/.cache/buildstream
    Log Files:               /home/user/.cache/buildstream/logs
    Source Mirrors:          /home/user/.cache/buildstream/sources
    Build Area:              /home/user/.cache/buildstream/build
    Strict Build Plan:       Yes
    Maximum Fetch Tasks:     10
    Maximum Build Tasks:     4
    Maximum Push Tasks:      4
    Maximum Network Retries: 2

Project: integration-commands

    Element Plugins
        manual: core plugin
        stack:  core plugin
        import: core plugin

    Source Plugins
        local: core plugin
        tar:   core plugin

Pipeline
   buildable 7b81cb08196aa99db72aaad24c7d53fea9bf381ffc99c0ba8408be7dcd0e31b5 base/alpine.bst 
     waiting b288c75d9d19ab925d7371ef301566e157cf8708cc6886c88f010eaa51257c21 base.bst 
     waiting 3322fc7920c650d4691fa58b8a60191a93f91ad64daedd0ebaec0657be64a065 libhello.bst 
     waiting aed4173cdbf3df44fb4c8063bf44c95942cab3bfc8763ae4b76151983cec8f03 hello.bst 
===============================================================================
[--:--:--][7b81cb08][   build:base/alpine.bst               ] START   integration-commands/base-alpine/7b81cb08-build.8098.log
[--:--:--][7b81cb08][   build:base/alpine.bst               ] START   Staging sources
[00:00:00][7b81cb08][   build:base/alpine.bst               ] SUCCESS Staging sources
[--:--:--][7b81cb08][   build:base/alpine.bst               ] START   Caching artifact
[00:00:00][7b81cb08][   build:base/alpine.bst               ] SUCCESS Caching artifact
[00:00:00][7b81cb08][   build:base/alpine.bst               ] SUCCESS integration-commands/base-alpine/7b81cb08-build.8098.log
[--:--:--][b288c75d][   build:base.bst                      ] START   integration-commands/base/b288c75d-build.8105.log
[--:--:--][b288c75d][   build:base.bst                      ] START   Caching artifact
[00:00:00][b288c75d][   build:base.bst                      ] SUCCESS Caching artifact
[00:00:00][b288c75d][   build:base.bst                      ] SUCCESS integration-commands/base/b288c75d-build.8105.log
[--:--:--][3322fc79][   build:libhello.bst                  ] START   integration-commands/libhello/3322fc79-build.8109.log
[--:--:--][3322fc79][   build:libhello.bst                  ] START   Staging dependencies
[00:00:00][3322fc79][   build:libhello.bst                  ] SUCCESS Staging dependencies
[--:--:--][3322fc79][   build:libhello.bst                  ] START   Running commands

    ldconfig "/usr/lib"

[00:00:01][3322fc79][   build:libhello.bst                  ] SUCCESS Running commands
[--:--:--][3322fc79][   build:libhello.bst                  ] START   Staging sources
[00:00:00][3322fc79][   build:libhello.bst                  ] SUCCESS Staging sources
[--:--:--][3322fc79][   build:libhello.bst                  ] START   Running commands

    make PREFIX="/usr"
    make -j1 PREFIX="/usr" DESTDIR="/buildstream-install" install

[00:00:00][3322fc79][   build:libhello.bst                  ] SUCCESS Running commands
[--:--:--][3322fc79][   build:libhello.bst                  ] START   Caching artifact
[00:00:00][3322fc79][   build:libhello.bst                  ] SUCCESS Caching artifact
[00:00:01][3322fc79][   build:libhello.bst                  ] SUCCESS integration-commands/libhello/3322fc79-build.8109.log
[--:--:--][aed4173c][   build:hello.bst                     ] START   integration-commands/hello/aed4173c-build.8160.log
[--:--:--][aed4173c][   build:hello.bst                     ] START   Staging dependencies
[00:00:00][aed4173c][   build:hello.bst                     ] SUCCESS Staging dependencies
[--:--:--][aed4173c][   build:hello.bst                     ] START   Running commands

    ldconfig "/usr/lib"

[00:00:01][aed4173c][   build:hello.bst                     ] SUCCESS Running commands
[--:--:--][aed4173c][   build:hello.bst                     ] START   Staging sources
[00:00:00][aed4173c][   build:hello.bst                     ] SUCCESS Staging sources
[--:--:--][aed4173c][   build:hello.bst                     ] START   Running commands

    make PREFIX="/usr"
    make -j1 PREFIX="/usr" DESTDIR="/buildstream-install" install

[00:00:00][aed4173c][   build:hello.bst                     ] SUCCESS Running commands
[--:--:--][aed4173c][   build:hello.bst                     ] START   Caching artifact
[00:00:00][aed4173c][   build:hello.bst                     ] SUCCESS Caching artifact
[00:00:01][aed4173c][   build:hello.bst                     ] SUCCESS integration-commands/hello/aed4173c-build.8160.log
[00:00:03][        ][    main:core activity                 ] SUCCESS Build

Pipeline Summary
    Total:       4
    Session:     4
    Fetch Queue: processed 0, skipped 4, failed 0 
    Build Queue: processed 4, skipped 0, failed 0

Observe in the build process above, the integration command declared on the base/alpine.bst element is run after staging the dependency artifacts into the build sandbox and before running any of the build commands, for both of the libhello.bst and hello.bst elements.

BuildStream assumes that commands which are to be run in the build sandbox need to be run in an integrated sandbox.

Tip

Integration commands can be taxing on your overall build process, because they need to run at the beginning of every build which runtime depends on the element declaring them.

For this reason, it is better to leave out more onerous tasks if they are not needed at software build time, and handle those specific tasks differently later in the pipeline, before deployment.

4.3.2. Run the hello world program

Unlike the previous chapters, this hello world program takes an argument, we can invoke the program using bst shell:

user@host:~/integration-commands$ bst shell hello.bst -- hello pony

[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Resolving cached state
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving cached state
[--:--:--][        ][    main:hello.bst                     ] START   Staging dependencies
[00:00:00][        ][    main:hello.bst                     ] SUCCESS Staging dependencies
[--:--:--][        ][    main:hello.bst                     ] START   Integrating sandbox
[--:--:--][        ][    main:hello.bst                     ] START   Running commands

    ldconfig "/usr/lib"

2020-08-19T14:56:28.070+0000 [8229:140593699473472] [buildboxcommon_runner.cpp:547] [WARNING] The --use-localcas option will be deprecated. LocalCAS support is now enabled by default.
2020-08-19T14:56:28.070+0000 [8229:140593699473472] [buildboxcommon_client.cpp:87] [INFO] Setting d_maxBatchTotalSizeBytes = 4128768 bytes by default
+ sh -e -c ldconfig "/usr/lib"
[00:00:01][        ][    main:hello.bst                     ] SUCCESS Running commands
[00:00:01][        ][    main:hello.bst                     ] SUCCESS Integrating sandbox
[--:--:--][        ][    main:hello.bst                     ] STATUS  Running command

    hello pony

2020-08-19T14:56:29.355+0000 [8250:140140575389760] [buildboxcommon_runner.cpp:547] [WARNING] The --use-localcas option will be deprecated. LocalCAS support is now enabled by default.
2020-08-19T14:56:29.356+0000 [8250:140140575389760] [buildboxcommon_client.cpp:87] [INFO] Setting d_maxBatchTotalSizeBytes = 4128768 bytes by default
Hello pony

Here we see again, the integration commands are also used when preparing the shell to launch a command.

4.4. Summary

In this chapter we’ve observed how integration commands work, and we now know about public data, which plugins can read from their dependencies in order to influence their build process.