analytics: relocate UUID to homebrew.analyticsuuid in .git/config

This way analytics related settings and parameters (currently
analyticsdisabled, analyticsmessage and analyticsuuid) are all kept in
the same place.

Note that in this commit we offer a path of migration: if
~/.homebrew_analytics_user_uuid already exists, read the UUID from it,
write to homebrew.analyticsuuid, and remove it.

See more detailed discussions in #145.

Closes #162.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>

2 files changed, 28 insertions, 14 deletions

diff --git a/Library/Homebrew/utils/analytics.sh b/Library/Homebrew/utils/analytics.sh
index 3c6fc59a0..47716e5e5 100644
--- a/Library/Homebrew/utils/analytics.sh
+++ b/Library/Homebrew/utils/analytics.sh
@@ -1,30 +1,44 @@
+# Migrate analytics UUID to its new home in Homebrew repo's git config and
+# remove the legacy UUID file if detected.
+migrate-legacy-uuid-file() {
+  local legacy_uuid_file="$HOME/.homebrew_analytics_user_uuid"
+  if [[ -f "$legacy_uuid_file" ]]
+  then
+    local analytics_uuid="$(<"$legacy_uuid_file")"
+    if [[ -n "$analytics_uuid" ]]
+    then
+      git config --file="$HOMEBREW_REPOSITORY/.git/config" --replace-all homebrew.analyticsuuid "$analytics_uuid"
+    fi
+    rm -f "$legacy_uuid_file"
+  fi
+}
+
 setup-analytics() {
-  # User UUID file. Used for Homebrew user counting. Can be deleted and
-  # recreated with no adverse effect (beyond our user counts being inflated).
-  HOMEBREW_ANALYTICS_USER_UUID_FILE="$HOME/.homebrew_analytics_user_uuid"
+  local git_config_file="$HOMEBREW_REPOSITORY/.git/config"
+
+  migrate-legacy-uuid-file
 
   # Make disabling anlytics sticky
   if [[ -n "$HOMEBREW_NO_ANALYTICS" ]]
   then
-    git config --file="$HOMEBREW_REPOSITORY/.git/config" --replace-all homebrew.analyticsdisabled true
-    # Internal variable for brew's use, to differentiate from user-supplied setting
-    export HOMEBREW_NO_ANALYTICS_THIS_RUN="1"
+    git config --file="$git_config_file" --replace-all homebrew.analyticsdisabled true
+    git config --file="$git_config_file" --unset-all homebrew.analyticsuuid
   fi
 
-  if [[ "$(git config --file="$HOMEBREW_REPOSITORY/.git/config" --get homebrew.analyticsmessage)" != "true" ||
-        "$(git config --file="$HOMEBREW_REPOSITORY/.git/config" --get homebrew.analyticsdisabled)" = "true" ]]
+  local message_seen="$(git config --file="$git_config_file" --get homebrew.analyticsmessage)"
+  local analytics_disabled="$(git config --file="$git_config_file" --get homebrew.analyticsdisabled)"
+  if [[ "$message_seen" != "true" || "$analytics_disabled" = "true" ]]
   then
-    [[ -f "$HOMEBREW_ANALYTICS_USER_UUID_FILE" ]] && rm -f "$HOMEBREW_ANALYTICS_USER_UUID_FILE"
+    # Internal variable for brew's use, to differentiate from user-supplied setting
     export HOMEBREW_NO_ANALYTICS_THIS_RUN="1"
     return
   fi
 
-  if [[ -r "$HOMEBREW_ANALYTICS_USER_UUID_FILE" ]]
+  HOMEBREW_ANALYTICS_USER_UUID="$(git config --file="$git_config_file" --get homebrew.analyticsuuid)"
+  if [[ -z "$HOMEBREW_ANALYTICS_USER_UUID" ]]
   then
-    HOMEBREW_ANALYTICS_USER_UUID="$(<"$HOMEBREW_ANALYTICS_USER_UUID_FILE")"
-  else
     HOMEBREW_ANALYTICS_USER_UUID="$(uuidgen)"
-    echo "$HOMEBREW_ANALYTICS_USER_UUID" > "$HOMEBREW_ANALYTICS_USER_UUID_FILE"
+    git config --file="$git_config_file" --replace-all homebrew.analyticsuuid "$HOMEBREW_ANALYTICS_USER_UUID"
   fi
 
   if [[ -n "$HOMEBREW_LINUX" ]]
diff --git a/share/doc/homebrew/Analytics.md b/share/doc/homebrew/Analytics.md
index e22f11607..2200335e1 100644
--- a/share/doc/homebrew/Analytics.md
+++ b/share/doc/homebrew/Analytics.md
@@ -13,7 +13,7 @@ Homebrew's analytics record some shared information for every event:
 - The Homebrew user agent e.g. `Homebrew/0.9.9 (Macintosh; Intel Mac OS X 10.11.4) curl/7.43.0`
 - The Google Analytics version i.e. `1` (https://developers.google.com/analytics/devguides/collection/protocol/v1/parameters#v)
 - The Homebrew analytics tracking ID e.g. `UA-75654628-1` (https://developers.google.com/analytics/devguides/collection/protocol/v1/parameters#tid)
-- A Homebrew analytics user ID e.g. `1BAB65CC-FE7F-4D8C-AB45-B7DB5A6BA9CB`. This is generated by `uuidgen` and stored in `~/.homebrew_analytics_user_uuid`. This does not allow us to track individual users but does enable us to accurately measure user counts vs. event counts (https://developers.google.com/analytics/devguides/collection/protocol/v1/parameters#cid)
+- A Homebrew analytics user ID e.g. `1BAB65CC-FE7F-4D8C-AB45-B7DB5A6BA9CB`. This is generated by `uuidgen` and stored in the repository-specific Git configuration variable `homebrew.analyticsuuid` within `$(brew --repository)/.git/config`. This does not allow us to track individual users but does enable us to accurately measure user counts vs. event counts (https://developers.google.com/analytics/devguides/collection/protocol/v1/parameters#cid)
 - The Google Analytics anonymous IP setting is enabled i.e. `1` (https://developers.google.com/analytics/devguides/collection/protocol/v1/parameters#aip)
 - The Homebrew application name e.g. `Homebrew` (https://developers.google.com/analytics/devguides/collection/protocol/v1/parameters#an)
 - The Homebrew application version e.g. `0.9.9` (https://developers.google.com/analytics/devguides/collection/protocol/v1/parameters#av)