https://github.com/backtrace-labs/invoker

ATS crash-logger replacement
https://github.com/backtrace-labs/invoker

Last synced: 7 months ago
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ATS crash-logger replacement

• Host: GitHub
• URL: https://github.com/backtrace-labs/invoker
• Owner: backtrace-labs
• License: mit
• Created: 2016-03-03T23:45:57.000Z (almost 10 years ago)
• Default Branch: master
• Last Pushed: 2016-10-06T17:20:16.000Z (over 9 years ago)
• Last Synced: 2025-04-02T15:43:28.468Z (10 months ago)
• Language: C
• Size: 34.2 KB
• Stars: 1
• Watchers: 15
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
### backtrace-invoker - Tracer Integration with ATS

To install:

- `./configure; make; make install` (For additional options, run `./configure --help`)

To uninstall:

- `make uninstall`

`backtrace-invoker` is a binary which will execute potentially multiple tracing

programs on a target process (or the parent process, if no target is specified).

It is meant to be a drop-in replacement for current crash logging processes

(e.g. `traffic_crashlog`) while providing the ability to run the replaced tracing

process in addition to the new one (e.g. `backtrace-ptrace`).

There are two options for integration:

- Modify `proxy.config.crash_log_helper` to point to the installation path for

`backtrace-invoker`.

- Replace `traffic_crashlog` binary in the configured location with the invoker

binary (keep the `traffic_crashlog` name)

All options currently used by `ATS` (`--syslog`, `--wait`, `--host`) are accepted,

though `--syslog` and `--host` are ignored.

Messages are logged to syslog (`LOG_DAEMON`) by default (`stderr` logging can be

enabled with `-d/--debug`).

Hostname is not used by the backtrace-ptrace tracer. `traffic_crashlog` uses it

to determine whether to read ucontext and siginfo from `stdin`; however,

`traffic_crashlog_helper` writes these to the pipe simply if `__linux__` is defined,

so that is all we check in invoker before reading this data from stdin.

ucontext and siginfo are not used by the `backtrace-ptrace` tracer, but these are

read from stdin regardless to keep parity with `traffic_crashlog`. As mentioned

above, this only applies to Linux systems.

A tracer may also be specified via the `INVOKER_TRACER` environment variable.

This is useful if one would like to avoid code changes but the desired tracer

requires specific parameters. For example, one might typically specify an output

directory to `backtrace-ptrace` via `-o ]

    -p, --target=            Target process to trace. If left

                                  unspecified, the parent process will be

                                  traced.

    -t, --tracer=      Tracer to run against the target process.

                                  If left unspecified, backtrace_ptrace will

                                  be used (from its standard installation

                                  directory [/opt/backtrace/bin]).

                                  A format string to pass into the specified

                                  tracer may be supplied as well.

                                  Supported replacements:

                                      %p: target pid

                                  Multiple tracers may be specified (up to a

                                  maximum of 16), and will be executed in order.

                                  If any of the tracers fail to exit successfully,

                                  subsequent tracers will not be executed.

    -w, --wait                    Suspends the process before invoking the

                                  tracer until receiving a SIGCONT. This

                                  exists for compatibility with ATS Crash

                                  Logger, and may be removed in the future.

    -n,                           Disables Apache Traffic Server compatibility

    --no-ats-compatibility        mode. Certain actions (reading from stdin)

                                  are necessary only to keep parity with ATS

                                  crash logger. This is currently enabled by

                                  default.

    -d, --debug                   Prints log messages to stderr instead of

                                  syslog.

    -v, --version                 Prints invoker version.

    -h, --help                    Prints this help message.

```