Allow graceful_terminator to bind to an old named pipe

Project.toml

@@ -1,7 +1,7 @@
 name = "K8sDeputy"
 uuid = "2481ae95-212f-4650-bb21-d53ea3caf09f"
 authors = ["Beacon Biosignals, Inc"]
-version = "0.1.0"
+version = "0.1.1"
 
 [deps]
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"

src/K8sDeputy.jl

@@ -10,5 +10,6 @@ export Deputy, graceful_terminator, readied!, shutdown!, graceful_terminate
 include("graceful_termination.jl")
 include("health.jl")
 include("server.jl")
+include("deprecated.jl")
 
 end # module K8sDeputy

src/deprecated.jl

@@ -0,0 +1,5 @@
+using Base: @deprecate
+
+@deprecate(graceful_terminate(pid::Integer; wait::Bool=true),
+           graceful_terminate(Int32(pid); wait),
+           true)

src/graceful_termination.jl

@@ -13,7 +13,8 @@ _deputy_ipc_dir() = get(tempdir, ENV, "DEPUTY_IPC_DIR")
 
 # Prefer using UNIX domain sockets but if the `DEPUTY_IPC_DIR` is set assume the file
 # system is read-only and use a named pipe instead.
-function _socket_path(name)
+function _graceful_terminator_socket_path(pid::Int32)
+    name = "graceful-terminator.$pid"
     return haskey(ENV, "DEPUTY_IPC_DIR") ? joinpath(_deputy_ipc_dir(), name) : name
 end
 
@@ -24,7 +25,7 @@ set_entrypoint_pid(pid::Integer) = write(entrypoint_pid_file(), string(pid) * "\
 
 function entrypoint_pid()
     pid_file = entrypoint_pid_file()
-    return isfile(pid_file) ? parse(Int, readchomp(pid_file)) : 1
+    return isfile(pid_file) ? parse(Int32, readchomp(pid_file)) : Int32(1)
 end
 
 # https://docs.libuv.org/en/v1.x/process.html#c.uv_kill
@@ -80,11 +81,19 @@ process and the `preStop` process to cleanly terminate.
 function graceful_terminator(f; set_entrypoint::Bool=true)
     set_entrypoint && set_entrypoint_pid(getpid())
 
-    # Utilize UNIX domain sockets for the IPC. Avoid using network sockets here as we don't
-    # want to allow access to this functionality from outside of the localhost. Each process
-    # uses a distinct socket name allowing for multiple Julia processes to allow independent
-    # use of the graceful terminator.
-    server = listen(_socket_path("graceful-terminator.$(getpid())"))
+    # Utilize UNIX domain sockets or named pipes for the IPC. Avoid using network sockets
+    # here as we don't want to allow access to this functionality from outside of the
+    # localhost. Each process uses a distinct socket name allowing for multiple Julia
+    # processes to allow independent use of the graceful terminator.
+    socket_path = _graceful_terminator_socket_path(getpid())
+
+    # Remove any pre-existing named pipe as otherwise this will cause our `listen` call to
+    # fail. Should be safe to remove this file as it has been reserved for this PID. Only
+    # should be needed in the scenarion where the K8s pod has been restarted and the
+    # location of the socket exists in a K8s volume.
+    ispath(socket_path) && rm(socket_path)
+
+    server = listen(socket_path)
 
     t = Threads.@spawn begin
         while isopen(server)
@@ -115,12 +124,12 @@ function graceful_terminator(f; set_entrypoint::Bool=true)
 end
 
 """
-    graceful_terminate(pid::Integer=entrypoint_pid(); wait::Bool=true) -> Nothing
+    graceful_terminate(pid::Int32=entrypoint_pid(); wait::Bool=true) -> Nothing
 
 Initiates the execution of the `graceful_terminator` user callback in the process `pid`. See
 `graceful_terminator` for more details.
 """
-function graceful_terminate(pid::Integer=entrypoint_pid(); wait::Bool=true)
+function graceful_terminate(pid::Int32=entrypoint_pid(); wait::Bool=true)
     # Note: The follow dead code has been left here purposefully as an example of how to
     # view output when running via `preStop`.
     #
@@ -131,7 +140,7 @@ function graceful_terminate(pid::Integer=entrypoint_pid(); wait::Bool=true)
     #     println(io, "preStop called")
     # end
 
-    sock = connect(_socket_path("graceful-terminator.$pid"))
+    sock = connect(_graceful_terminator_socket_path(pid))
     println(sock, "terminate")
     close(sock)
 

test/graceful_termination.jl

@@ -71,4 +71,59 @@
         @test output1 == expected
         @test output2 == expected
     end
+
+    # When users set `DEPUTY_IPC_DIR` they may be using a K8s volume. As even `emptyDir`
+    # volumes persist for the lifetime of the pod we may have a named pipe already present
+    # from a previous restart.
+    @testset "bind after restart" begin
+        deputy_ipc_dir = mktempdir()
+        code = quote
+            using K8sDeputy
+            using Sockets: listen
+
+            # Generate the socket as if the K8s pod had restarted and this path remained.
+            # One difference with this setup is the process which created the socket is
+            # still running so there may be a write lock on the file which definitely
+            # wouldn't exist if the pod had restarted. Note that closing the socket will
+            # remove the path.
+            socket_path = K8sDeputy._graceful_terminator_socket_path(getpid())
+            server = listen(socket_path)
+
+            atexit(() -> @info "SHUTDOWN COMPLETE")
+            graceful_terminator(; set_entrypoint=false) do
+                @info "GRACEFUL TERMINATION HANDLER"
+                exit(2)
+                return nothing
+            end
+            sleep(60)
+        end
+
+        cmd = `$(Base.julia_cmd()) --color=no -e $code`
+
+        withenv("DEPUTY_IPC_DIR" => deputy_ipc_dir) do
+            buffer = IOBuffer()
+            p = run(pipeline(cmd; stdout=buffer, stderr=buffer); wait=false)
+            @test timedwait(() -> process_running(p), Second(5)) === :ok
+
+            # Allow some time for Julia to startup and the graceful terminator to be registered.
+            sleep(3)
+
+            # Socket exists as a named pipe
+            socket_path = K8sDeputy._graceful_terminator_socket_path(getpid(p))
+            @test ispath(socket_path)
+            @test !isfile(socket_path)
+
+            # Blocks untils the process terminates
+            @test graceful_terminate(getpid(p)) === nothing
+            @test process_exited(p)
+            @test p.exitcode == 2
+
+            output = String(take!(buffer))
+            expected = """
+                [ Info: GRACEFUL TERMINATION HANDLER
+                [ Info: SHUTDOWN COMPLETE
+                """
+            @test output == expected
+        end
+    end
 end