packaging: add git commit info (#5049)

* packaging: generate git commit info

Signed-off-by: Patrick Stephens <pat@calyptia.com>

* packaging: print git commit info

Signed-off-by: Patrick Stephens <pat@calyptia.com>

* packaging: print git commit info

Signed-off-by: Patrick Stephens <pat@calyptia.com>

* packaging: tidy up comments

Signed-off-by: Patrick Stephens <pat@calyptia.com>

Author: patrick-stephens

.dockerignore

@@ -1,3 +1,4 @@
-.git
+# We need the git commit info
+# .git
 build/**
 dockerfiles/**

CMakeLists.txt

@@ -317,6 +317,18 @@ if(CMAKE_SYSTEM_NAME MATCHES "Darwin")
   endif()
 endif()
 
+# Extract Git commit information for debug output.
+# Note that this is only set when cmake is run, the intent here is to use in CI for verification of releases so is acceptable.
+# For a better solution see https://jonathanhamberg.com/post/cmake-embedding-git-hash/ but this is simple and easy.
+find_package(Git)
+# If we do not have Git or this is not a Git repo or another error this just is ignored and we have no output at runtime.
+execute_process(COMMAND
+  "${GIT_EXECUTABLE}" log -1 --format=%H
+  WORKING_DIRECTORY "${FLB_ROOT}"
+  OUTPUT_VARIABLE FLB_GIT_HASH
+  ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
+message(STATUS "Git hash: ${FLB_GIT_HASH}")
+
 # Optional features like Stream Processor and Record Accessor needs Flex
 # and Bison to generate it parsers.
 find_package(FLEX 2)

dockerfiles/Dockerfile

@@ -38,6 +38,7 @@ RUN apt-get update && \
     curl \
     ca-certificates \
     cmake \
+    git \
     make \
     tar \
     libssl-dev \

include/fluent-bit/flb_version.h.in

@@ -33,4 +33,6 @@
                              FLB_VERSION_PATCH)
 #define FLB_VERSION_STR     "@FLB_VERSION_STR@"
 
+#define FLB_GIT_HASH        "@FLB_GIT_HASH@"
+
 #endif

src/fluent-bit.c

@@ -97,6 +97,7 @@ static void flb_version()
 #else
     printf("Fluent Bit v%s\n", FLB_VERSION_STR);
 #endif
+    printf("Git commit: %s\n", FLB_GIT_HASH);
 
     exit(EXIT_SUCCESS);
 }
@@ -111,7 +112,7 @@ static void flb_banner()
     fprintf(stderr,
             "%sFluent Bit v%s%s\n", ANSI_BOLD, FLB_VERSION_STR, ANSI_RESET);
 #endif
-
+    fprintf(stderr, "* Git commit: %s\n", FLB_GIT_HASH);
     fprintf(stderr, "* %sCopyright (C) 2015-2021 The Fluent Bit Authors%s\n",
             ANSI_BOLD ANSI_YELLOW, ANSI_RESET);
     fprintf(stderr, "* Fluent Bit is a CNCF sub-project under the "