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                 ] STATUS  Cache usage recomputed: 12K / infinity (0%)
[--:--:--][        ][ 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 1.3.0+1567.g067a0c6b.dirty
  Session Start: Monday, 18-02-2019 at 20:39:50
  Project:       integration-commands (/home/user/integration-commands)
  Targets:       hello.bst
  Cache Usage:   12K / infinity (0%)

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

Pipeline
   buildable f8700cb48e2c26e9a1d7f98c26edc90048217491282fa53b3e3d93f971633e0c base/alpine.bst 
     waiting 01431d85395431ae6ef96907a6416ea5e9d2c18862ba5428153c0ec16337e110 base.bst 
     waiting 3e55e626ff72b7f77d6efe2e5160ccd6d9269da817763d2a6ff1ef271b4b6cb0 libhello.bst 
     waiting 5430c9526aaed331b94d5073a8007a4d8be9cbdf8141166e47c4b7c0cda53cbc hello.bst 
===============================================================================
[--:--:--][f8700cb4][build:base/alpine.bst               ] START   integration-commands/base-alpine/f8700cb4-build.4090.log
[--:--:--][f8700cb4][build:base/alpine.bst               ] START   Staging sources
[00:00:20][f8700cb4][build:base/alpine.bst               ] SUCCESS Staging sources
[--:--:--][f8700cb4][build:base/alpine.bst               ] START   Caching artifact
[00:00:09][f8700cb4][build:base/alpine.bst               ] SUCCESS Caching artifact
[00:00:35][f8700cb4][build:base/alpine.bst               ] SUCCESS integration-commands/base-alpine/f8700cb4-build.4090.log
[--:--:--][01431d85][build:base.bst                      ] START   integration-commands/base/01431d85-build.4095.log
[--:--:--][01431d85][build:base.bst                      ] START   Caching artifact
[00:00:00][01431d85][build:base.bst                      ] SUCCESS Caching artifact
[00:00:00][01431d85][build:base.bst                      ] SUCCESS integration-commands/base/01431d85-build.4095.log
[--:--:--][3e55e626][build:libhello.bst                  ] START   integration-commands/libhello/3e55e626-build.4100.log
[--:--:--][3e55e626][build:libhello.bst                  ] START   Staging dependencies
[00:00:01][3e55e626][build:libhello.bst                  ] SUCCESS Staging dependencies
[--:--:--][3e55e626][build:libhello.bst                  ] START   Integrating sandbox
[--:--:--][3e55e626][build:libhello.bst                  ] STATUS  Running command

    ldconfig "/usr/lib"

[00:00:00][3e55e626][build:libhello.bst                  ] SUCCESS Integrating sandbox
[--:--:--][3e55e626][build:libhello.bst                  ] START   Staging sources
[00:00:00][3e55e626][build:libhello.bst                  ] SUCCESS Staging sources
[--:--:--][3e55e626][build:libhello.bst                  ] START   Running build-commands
[--:--:--][3e55e626][build:libhello.bst                  ] STATUS  Running command

    make PREFIX="/usr"

[00:00:00][3e55e626][build:libhello.bst                  ] SUCCESS Running build-commands
[--:--:--][3e55e626][build:libhello.bst                  ] START   Running install-commands
[--:--:--][3e55e626][build:libhello.bst                  ] STATUS  Running command

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

[00:00:00][3e55e626][build:libhello.bst                  ] SUCCESS Running install-commands
[--:--:--][3e55e626][build:libhello.bst                  ] START   Running strip-commands
[00:00:00][3e55e626][build:libhello.bst                  ] SUCCESS Running strip-commands
[--:--:--][3e55e626][build:libhello.bst                  ] START   Caching artifact
[00:00:00][3e55e626][build:libhello.bst                  ] SUCCESS Caching artifact
[00:00:02][3e55e626][build:libhello.bst                  ] SUCCESS integration-commands/libhello/3e55e626-build.4100.log
[--:--:--][5430c952][build:hello.bst                     ] START   integration-commands/hello/5430c952-build.4129.log
[--:--:--][5430c952][build:hello.bst                     ] START   Staging dependencies
[00:00:01][5430c952][build:hello.bst                     ] SUCCESS Staging dependencies
[--:--:--][5430c952][build:hello.bst                     ] START   Integrating sandbox
[--:--:--][5430c952][build:hello.bst                     ] STATUS  Running command

    ldconfig "/usr/lib"

[00:00:00][5430c952][build:hello.bst                     ] SUCCESS Integrating sandbox
[--:--:--][5430c952][build:hello.bst                     ] START   Staging sources
[00:00:00][5430c952][build:hello.bst                     ] SUCCESS Staging sources
[--:--:--][5430c952][build:hello.bst                     ] START   Running build-commands
[--:--:--][5430c952][build:hello.bst                     ] STATUS  Running command

    make PREFIX="/usr"

[00:00:00][5430c952][build:hello.bst                     ] SUCCESS Running build-commands
[--:--:--][5430c952][build:hello.bst                     ] START   Running install-commands
[--:--:--][5430c952][build:hello.bst                     ] STATUS  Running command

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

[00:00:00][5430c952][build:hello.bst                     ] SUCCESS Running install-commands
[--:--:--][5430c952][build:hello.bst                     ] START   Running strip-commands
[00:00:00][5430c952][build:hello.bst                     ] SUCCESS Running strip-commands
[--:--:--][5430c952][build:hello.bst                     ] START   Caching artifact
[00:00:00][5430c952][build:hello.bst                     ] SUCCESS Caching artifact
[00:00:02][5430c952][build:hello.bst                     ] SUCCESS integration-commands/hello/5430c952-build.4129.log
[00:00:40][        ][ 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
[--:--:--][5430c952][ main:hello.bst                     ] START   Staging dependencies
[00:00:01][5430c952][ main:hello.bst                     ] SUCCESS Staging dependencies
[--:--:--][5430c952][ main:hello.bst                     ] START   Integrating sandbox
[--:--:--][5430c952][ main:hello.bst                     ] STATUS  Running command

    ldconfig "/usr/lib"

[00:00:00][5430c952][ main:hello.bst                     ] SUCCESS Integrating sandbox
[--:--:--][5430c952][ main:hello.bst                     ] STATUS  Running command

    hello pony

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.