logging: Add possibility to log into file (#2008)

Add processing of environment variables LOGPATH and LOG_PATH
If either one exists - logger will log into the file on that
path instead of STDOUT.

refs: #2000

Signed-off-by: Konstantin Yarovoy <[email protected]>

Author: Konstantin

USAGE.md

@@ -47,6 +47,13 @@ crystal src/cnf-testsuite.cr <testname>
 
 ---
 
+### Logging Parameters
+
+- **LOG_LEVEL** environment variable: sets minimal log level to display: error (default); info; debug.
+- **LOG_PATH** environment variable: if set - all logs would be appended to the file defined by that variable.
+
+---
+
 ### Common Example Commands
 
 #### Building the executable

spec/utils/utils_spec.cr

@@ -258,6 +258,18 @@ describe "Utils" do
     CNFManager.sample_cleanup(config_file: "sample-cnfs/sample-coredns-cnf", verbose: true)
   end
 
+  it "'logger' should write logs to the file when LOG_PATH is set", tags: ["logger"] do
+    response_s = `LOG_PATH=spec-test-testsuite.log ./cnf-testsuite test`
+    $?.success?.should be_true
+    (/ERROR -- cnf-testsuite: error test/ =~ response_s).should be_nil
+    File.exists?("spec-test-testsuite.log").should be_true
+    (/ERROR -- cnf-testsuite: error test/ =~ File.read("spec-test-testsuite.log")).should_not be_nil
+  ensure
+    if File.exists?("spec-test-testsuite.log")
+      File.delete("spec-test-testsuite.log")
+    end
+  end
+
   it "'#update_yml' should update the value for a key in a yml file", tags: ["logger"]  do
     begin
     update_yml("spec/fixtures/cnf-testsuite.yml", "release_name", "coredns --set worker-node='kind-control-plane'")

src/tasks/utils/utils.cr

@@ -82,9 +82,24 @@ end
 
 # this first line necessary to make sure our custom formatter
 # is used in the default error log line also
-Log.setup(Log::Severity::Error, Log::IOBackend.new(formatter: log_formatter))
-Log.setup(loglevel, Log::IOBackend.new(formatter: log_formatter))
+Log.setup(Log::Severity::Error, log_backend)
+Log.setup(loglevel, log_backend)
 
+def log_backend
+  if ENV.has_key?("LOGPATH") || ENV.has_key?("LOG_PATH")
+    log_file = ENV.has_key?("LOGPATH") ? ENV["LOGPATH"] : ENV["LOG_PATH"]
+  else
+    log_file = ""
+  end
+  
+  if log_file.empty?
+    backend = Log::IOBackend.new(formatter: log_formatter)
+  else
+    log_io = File.open(log_file, "a")
+    backend = Log::IOBackend.new(io: log_io, formatter: log_formatter)
+  end
+  backend
+end
 
 def loglevel
   levelstr = "" # default to unset