Several environment variables and control files control the behaviour of debuginfod client applications.
This environment variable points to a file system to be used for temporary files. The default is /tmp.
This environment variable contains a list of URL prefixes for trusted debuginfod instances. Alternate URL prefixes are separated by space. This environment variable may be set by /etc/profile.d scripts reading /etc/debuginfod/*.urls files.
This environment variable governs the location of the cache where downloaded files and cache-control files are kept. The default directory is chosen based on other environment variables, see below.
This environment variable governs the default progress function. If set, and if a progressfn is not explicitly set, then the library will configure a default progressfn. This function will append a simple progress message periodically to stderr. The default is no progress function output.
This environment variable governs the default file descriptor for verbose output. If set, and if a verbose fd is not explicitly set, then the verbose output will be produced on STDERR_FILENO.
This environment variable governs the default limit of retry attempts. If a query failed with errno other than ENOENT, will initiate several attempts within the limit.
This environment variable governs the download commencing timeout for each debuginfod HTTP connection. A server that fails to provide at least 100K of data within this many seconds is skipped. The default is 90 seconds. (Zero or negative means "no timeout".)
This environment variable dictates how long the client will wait to complete the download a file found on a server in seconds. It is best used to ensure that a file is downloaded quickly or be rejected. The default is 0 (infinite time).
This environment variable dictates the maximum size of a file to download in bytes. This is best used if the user would like to ensure only small files are downloaded. A value of 0 causes no consideration for size, and the client may attempt to download a file of any size. The default is 0 (infinite size).
This environment variable points to a file that supplies headers to outbound HTTP requests, one per line. The header lines shouldn't end with CRLF, unless that's the system newline convention. Whitespace-only lines are skipped.
Before each query, the debuginfod client library checks for a need to clean the cache. If it's time to clean, the library traverses the cache directory and removes downloaded debuginfo-related artifacts and newly empty directories, if they have not been accessed recently.
Control files are located directly under the cache directory. They contain simple decimal numbers to set cache-related configuration parameters. If the files do not exist, the client library creates the files with the default parameter values as content.
After each query, the debuginfod client library deposits newly received files into a directory & file that is named based on the build-id. A failed query is also cached by a special file. The naming convention used for these artifacts is deliberately undocumented.
Default cache directory, if $XDG_CACHE_HOME is set.
Default cache directory, if $XDG_CACHE_HOME is not set.
Deprecated cache directory, used only if preexisting.
This control file gives the interval between cache cleaning rounds, in seconds. The default is 86400, one day. 0 means "immediately".
This control file sets how long unaccessed debuginfo-related files are retained, in seconds. The default is 604800, one week. 0 means "immediately".
This control file sets how long to remember a query failure, in seconds. New queries for the same artifacts within this time window are short-circuited (returning an immediate failure instead of sending a new query to servers). This accelerates queries that probably would still fail. The default is 600, 10 minutes. 0 means "forget immediately".