refactor main loop into multiple functions

This also gains the ability to report errors when posting the response
This commit is contained in:
Emil Lerch 2023-08-02 17:36:22 -07:00
parent 883bc6f52f
commit e2bbaf2c9a
Signed by untrusted user: lobo
GPG Key ID: A7B62D657EF764F8

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@ -5,11 +5,21 @@ const HandlerFn = *const fn (std.mem.Allocator, []const u8) anyerror![]const u8;
const log = std.log.scoped(.lambda);
var empty_headers: std.http.Headers = undefined;
var client: ?std.http.Client = null;
const prefix = "http://";
const postfix = "/2018-06-01/runtime/invocation";
pub fn deinit() void {
if (client) |*c| c.deinit();
client = null;
}
/// Starts the lambda framework. Handler will be called when an event is processing
/// If an allocator is not provided, an approrpriate allocator will be selected and used
/// This function is intended to loop infinitely. If not used in this manner,
/// make sure to call the deinit() function
pub fn run(allocator: ?std.mem.Allocator, event_handler: HandlerFn) !void { // TODO: remove inferred error set?
const prefix = "http://";
const postfix = "/2018-06-01/runtime/invocation";
const lambda_runtime_uri = std.os.getenv("AWS_LAMBDA_RUNTIME_API") orelse test_lambda_runtime_uri.?;
// TODO: If this is null, go into single use command line mode
@ -21,9 +31,13 @@ pub fn run(allocator: ?std.mem.Allocator, event_handler: HandlerFn) !void { // T
defer alloc.free(url);
const uri = try std.Uri.parse(url);
var client: std.http.Client = .{ .allocator = alloc };
defer client.deinit();
var empty_headers = std.http.Headers.init(alloc);
// TODO: Simply adding this line without even using the client is enough
// to cause seg faults!?
// client = client orelse .{ .allocator = alloc };
// so we'll do this instead
if (client != null) return error.MustDeInitBeforeCallingRunAgain;
client = .{ .allocator = alloc };
empty_headers = std.http.Headers.init(alloc);
defer empty_headers.deinit();
log.info("tid {d} (lambda): Bootstrap initializing with event url: {s}", .{ std.Thread.getCurrentId(), url });
@ -36,160 +50,229 @@ pub fn run(allocator: ?std.mem.Allocator, event_handler: HandlerFn) !void { // T
var req_alloc = std.heap.ArenaAllocator.init(alloc);
defer req_alloc.deinit();
const req_allocator = req_alloc.allocator();
var req = try client.request(.GET, uri, empty_headers, .{});
defer req.deinit();
req.start() catch |err| { // Well, at this point all we can do is shout at the void
log.err("Get fail (start): {}", .{err});
std.os.exit(0);
// Fundamentally we're doing 3 things:
// 1. Get the next event from Lambda (event data and request id)
// 2. Call our handler to get the response
// 3. Post the response back to Lambda
var ev = getEvent(req_allocator, uri) catch |err| {
// Well, at this point all we can do is shout at the void
log.err("Error fetching event details: {}", .{err});
std.os.exit(1);
// continue;
};
if (ev == null) continue; // this gets logged in getEvent, and without
// a request id, we still can't do anything
// reasonable to report back
const event = ev.?;
defer ev.?.deinit();
const event_response = event_handler(req_allocator, event.event_data) catch |err| {
event.reportError(@errorReturnTrace(), err, lambda_runtime_uri) catch unreachable;
continue;
};
// Lambda freezes the process at this line of code. During warm start,
// the process will unfreeze and data will be sent in response to client.get
req.wait() catch |err| { // Well, at this point all we can do is shout at the void
log.err("Get fail (wait): {}", .{err});
std.os.exit(0);
event.postResponse(lambda_runtime_uri, event_response) catch |err| {
event.reportError(@errorReturnTrace(), err, lambda_runtime_uri) catch unreachable;
continue;
};
}
}
const Event = struct {
allocator: std.mem.Allocator,
event_data: []u8,
request_id: []u8,
const Self = @This();
pub fn init(allocator: std.mem.Allocator, event_data: []u8, request_id: []u8) Self {
return .{
.allocator = allocator,
.event_data = event_data,
.request_id = request_id,
};
}
pub fn deinit(self: *Self) void {
self.allocator.free(self.event_data);
self.allocator.free(self.request_id);
}
fn reportError(
self: Self,
return_trace: ?*std.builtin.StackTrace,
err: anytype,
lambda_runtime_uri: []const u8,
) !void {
// If we fail in this function, we're pretty hosed up
if (return_trace) |rt|
log.err("Caught error: {}. Return Trace: {any}", .{ err, rt })
else
log.err("Caught error: {}. No return trace available", .{err});
const err_url = try std.fmt.allocPrint(
self.allocator,
"{s}{s}{s}/{s}/error",
.{ prefix, lambda_runtime_uri, postfix, self.request_id },
);
defer self.allocator.free(err_url);
const err_uri = try std.Uri.parse(err_url);
const content =
\\{{
\\ "errorMessage": "{s}",
\\ "errorType": "HandlerReturnedError",
\\ "stackTrace": [ "{any}" ]
\\}}
;
const content_fmt = if (return_trace) |rt|
try std.fmt.allocPrint(self.allocator, content, .{ @errorName(err), rt })
else
try std.fmt.allocPrint(self.allocator, content, .{ @errorName(err), "no return trace available" });
defer self.allocator.free(content_fmt);
log.err("Posting to {s}: Data {s}", .{ err_url, content_fmt });
var err_headers = std.http.Headers.init(self.allocator);
defer err_headers.deinit();
err_headers.append(
"Lambda-Runtime-Function-Error-Type",
"HandlerReturned",
) catch |append_err| {
log.err("Error appending error header to post response for request id {s}: {}", .{ self.request_id, append_err });
std.os.exit(1);
};
// TODO: There is something up with using a shared client in this way
// so we're taking a perf hit in favor of stability. In a practical
// sense, without making HTTPS connections (lambda environment is
// non-ssl), this shouldn't be a big issue
var cl = std.http.Client{ .allocator = self.allocator };
defer cl.deinit();
var req = try cl.request(.POST, err_uri, empty_headers, .{});
// var req = try client.?.request(.POST, err_uri, empty_headers, .{});
// defer req.deinit();
req.transfer_encoding = .{ .content_length = content_fmt.len };
req.start() catch |post_err| { // Well, at this point all we can do is shout at the void
log.err("Error posting response (start) for request id {s}: {}", .{ self.request_id, post_err });
std.os.exit(1);
};
try req.writeAll(content_fmt);
try req.finish();
req.wait() catch |post_err| { // Well, at this point all we can do is shout at the void
log.err("Error posting response (wait) for request id {s}: {}", .{ self.request_id, post_err });
std.os.exit(1);
};
// TODO: Determine why this post is not returning
if (req.response.status != .ok) {
// Documentation says something about "exit immediately". The
// Lambda infrastrucutre restarts, so it's unclear if that's necessary.
// It seems as though a continue should be fine, and slightly faster
// std.os.exit(1);
log.err("Get fail: {} {s}", .{
@intFromEnum(req.response.status),
req.response.status.phrase() orelse "",
});
continue;
std.os.exit(1);
}
var request_id: ?[]const u8 = null;
var content_length: ?usize = null;
for (req.response.headers.list.items) |h| {
if (std.ascii.eqlIgnoreCase(h.name, "Lambda-Runtime-Aws-Request-Id"))
request_id = h.value;
if (std.ascii.eqlIgnoreCase(h.name, "Content-Length")) {
content_length = std.fmt.parseUnsigned(usize, h.value, 10) catch null;
if (content_length == null)
log.warn("Error parsing content length value: '{s}'", .{h.value});
}
// TODO: XRay uses an environment variable to do its magic. It's our
// responsibility to set this, but no zig-native setenv(3)/putenv(3)
// exists. I would kind of rather not link in libc for this,
// so we'll hold for now and think on this
// if (std.mem.indexOf(u8, h.name.value, "Lambda-Runtime-Trace-Id")) |_|
// std.process.
// std.os.setenv("AWS_LAMBDA_RUNTIME_API");
}
if (request_id == null) {
// We can't report back an issue because the runtime error reporting endpoint
// uses request id in its path. So the best we can do is log the error and move
// on here.
log.err("Could not find request id: skipping request", .{});
continue;
}
const req_id = request_id.?;
log.debug("got lambda request with id {s}", .{req_id});
const reader = req.reader();
var buf: [65535]u8 = undefined;
var resp_payload = std.ArrayList(u8).init(req_allocator);
if (content_length) |len| {
resp_payload.ensureTotalCapacity(len) catch {
log.err("Could not allocate memory for body of request id: {s}", .{request_id.?});
continue;
};
}
defer resp_payload.deinit();
while (true) {
const read = try reader.read(&buf);
try resp_payload.appendSlice(buf[0..read]);
if (read == 0) break;
}
const event_response = event_handler(req_allocator, resp_payload.items) catch |err| {
// Stack trace will return null if stripped
const return_trace = @errorReturnTrace();
if (return_trace) |rt|
log.err("Caught error: {}. Return Trace: {any}", .{ err, rt })
else
log.err("Caught error: {}. No return trace available", .{err});
const err_url = try std.fmt.allocPrint(req_allocator, "{s}{s}/runtime/invocation/{s}/error", .{ prefix, lambda_runtime_uri, req_id });
defer req_allocator.free(err_url);
const err_uri = try std.Uri.parse(err_url);
const content =
\\ {s}
\\ "errorMessage": "{s}",
\\ "errorType": "HandlerReturnedError",
\\ "stackTrace": [ "{any}" ]
\\ {s}
;
const content_fmt = if (return_trace) |rt|
try std.fmt.allocPrint(req_allocator, content, .{ "{", @errorName(err), rt, "}" })
else
try std.fmt.allocPrint(req_allocator, content, .{ "{", @errorName(err), "no return trace available", "}" });
defer req_allocator.free(content_fmt);
log.err("Posting to {s}: Data {s}", .{ err_url, content_fmt });
var err_headers = std.http.Headers.init(req_allocator);
defer err_headers.deinit();
err_headers.append(
"Lambda-Runtime-Function-Error-Type",
"HandlerReturned",
) catch |append_err| {
log.err("Error appending error header to post response for request id {s}: {}", .{ req_id, append_err });
std.os.exit(0);
continue;
};
var err_req = try client.request(.POST, err_uri, empty_headers, .{});
defer err_req.deinit();
err_req.start() catch |post_err| { // Well, at this point all we can do is shout at the void
log.err("Error posting response for request id {s}: {}", .{ req_id, post_err });
std.os.exit(0);
continue;
};
err_req.wait() catch |post_err| { // Well, at this point all we can do is shout at the void
log.err("Error posting response for request id {s}: {}", .{ req_id, post_err });
std.os.exit(0);
continue;
};
// TODO: Determine why this post is not returning
if (err_req.response.status != .ok) {
// Documentation says something about "exit immediately". The
// Lambda infrastrucutre restarts, so it's unclear if that's necessary.
// It seems as though a continue should be fine, and slightly faster
// std.os.exit(1);
log.err("Get fail: {} {s}", .{
@intFromEnum(err_req.response.status),
err_req.response.status.phrase() orelse "",
});
continue;
}
log.err("Post complete", .{});
continue;
};
// TODO: We should catch these potential alloc errors too
// TODO: This whole loop should be in another function so we can catch everything at once
const response_url = try std.fmt.allocPrint(req_allocator, "{s}{s}{s}/{s}/response", .{ prefix, lambda_runtime_uri, postfix, req_id });
defer req_allocator.free(response_url);
const response_uri = try std.Uri.parse(response_url);
const response_content = try std.fmt.allocPrint(req_allocator, "{s} \"content\": \"{s}\" {s}", .{ "{", event_response, "}" });
var resp_req = try client.request(.POST, response_uri, empty_headers, .{});
defer resp_req.deinit();
resp_req.transfer_encoding = .{ .content_length = response_content.len };
try resp_req.start();
try resp_req.writeAll(response_content); // TODO: AllocPrint + writeAll makes no sense
try resp_req.finish();
resp_req.wait() catch |err| {
// TODO: report error
log.err("Error posting response for request id {s}: {}", .{ req_id, err });
continue;
};
log.err("Error reporting post complete", .{});
}
fn postResponse(self: Self, lambda_runtime_uri: []const u8, event_response: []const u8) !void {
const response_url = try std.fmt.allocPrint(
self.allocator,
"{s}{s}{s}/{s}/response",
.{ prefix, lambda_runtime_uri, postfix, self.request_id },
);
defer self.allocator.free(response_url);
const response_uri = try std.Uri.parse(response_url);
var cl = std.http.Client{ .allocator = self.allocator };
defer cl.deinit();
var req = try cl.request(.POST, response_uri, empty_headers, .{});
// var req = try client.?.request(.POST, response_uri, empty_headers, .{});
defer req.deinit();
const response_content = try std.fmt.allocPrint(
self.allocator,
"{{ \"content\": \"{s}\" }}",
.{event_response},
);
defer self.allocator.free(response_content);
req.transfer_encoding = .{ .content_length = response_content.len };
try req.start();
try req.writeAll(response_content);
try req.finish();
try req.wait();
}
};
fn getEvent(allocator: std.mem.Allocator, event_data_uri: std.Uri) !?Event {
// TODO: There is something up with using a shared client in this way
// so we're taking a perf hit in favor of stability. In a practical
// sense, without making HTTPS connections (lambda environment is
// non-ssl), this shouldn't be a big issue
var cl = std.http.Client{ .allocator = allocator };
defer cl.deinit();
var req = try cl.request(.GET, event_data_uri, empty_headers, .{});
// var req = try client.?.request(.GET, event_data_uri, empty_headers, .{});
// defer req.deinit();
try req.start();
try req.finish();
// Lambda freezes the process at this line of code. During warm start,
// the process will unfreeze and data will be sent in response to client.get
try req.wait();
if (req.response.status != .ok) {
// Documentation says something about "exit immediately". The
// Lambda infrastrucutre restarts, so it's unclear if that's necessary.
// It seems as though a continue should be fine, and slightly faster
// std.os.exit(1);
log.err("Lambda server event response returned bad error code: {} {s}", .{
@intFromEnum(req.response.status),
req.response.status.phrase() orelse "",
});
return error.EventResponseNotOkResponse;
}
var request_id: ?[]const u8 = null;
var content_length: ?usize = null;
for (req.response.headers.list.items) |h| {
if (std.ascii.eqlIgnoreCase(h.name, "Lambda-Runtime-Aws-Request-Id"))
request_id = h.value;
if (std.ascii.eqlIgnoreCase(h.name, "Content-Length")) {
content_length = std.fmt.parseUnsigned(usize, h.value, 10) catch null;
if (content_length == null)
log.warn("Error parsing content length value: '{s}'", .{h.value});
}
// TODO: XRay uses an environment variable to do its magic. It's our
// responsibility to set this, but no zig-native setenv(3)/putenv(3)
// exists. I would kind of rather not link in libc for this,
// so we'll hold for now and think on this
// if (std.mem.indexOf(u8, h.name.value, "Lambda-Runtime-Trace-Id")) |_|
// std.process.
// std.os.setenv("AWS_LAMBDA_RUNTIME_API");
}
if (request_id == null) {
// We can't report back an issue because the runtime error reporting endpoint
// uses request id in its path. So the best we can do is log the error and move
// on here.
log.err("Could not find request id: skipping request", .{});
return null;
}
if (content_length == null) {
// We can't report back an issue because the runtime error reporting endpoint
// uses request id in its path. So the best we can do is log the error and move
// on here.
log.err("No content length provided for event data", .{});
return null;
}
const req_id = request_id.?;
log.debug("got lambda request with id {s}", .{req_id});
var resp_payload = try std.ArrayList(u8).initCapacity(allocator, content_length.?);
defer resp_payload.deinit();
try resp_payload.resize(content_length.?);
var response_data = try resp_payload.toOwnedSlice();
errdefer allocator.free(response_data);
_ = try req.readAll(response_data);
return Event.init(
allocator,
response_data,
try allocator.dupe(u8, req_id),
);
}
////////////////////////////////////////////////////////////////////////
@ -320,7 +403,7 @@ fn test_run(allocator: std.mem.Allocator, event_handler: HandlerFn) !std.Thread
);
}
fn lambda_request(allocator: std.mem.Allocator, request: []const u8) ![]u8 {
fn lambda_request(allocator: std.mem.Allocator, request: []const u8, request_count: usize) ![]u8 {
var arena = std.heap.ArenaAllocator.init(allocator);
defer arena.deinit();
var aa = arena.allocator();
@ -344,7 +427,7 @@ fn lambda_request(allocator: std.mem.Allocator, request: []const u8) ![]u8 {
// booleans to know when to shut down. This function is designed for a
// single request/response pair only
lambda_remaining_requests = 1; // in case anyone messed with this, we will make sure we start
lambda_remaining_requests = request_count;
server_remaining_requests = lambda_remaining_requests.? * 2; // Lambda functions
// fetch from the server,
// then post back. Always
@ -379,7 +462,25 @@ test "basic request" {
const expected_response =
\\{ "content": "{"foo": "bar", "baz": "qux"}" }
;
const lambda_response = try lambda_request(allocator, request);
const lambda_response = try lambda_request(allocator, request, 1);
defer deinit();
defer allocator.free(lambda_response);
try std.testing.expectEqualStrings(expected_response, lambda_response);
}
test "several requests do not fail" {
// std.testing.log_level = .debug;
const allocator = std.testing.allocator;
const request =
\\{"foo": "bar", "baz": "qux"}
;
// This is what's actually coming back. Is this right?
const expected_response =
\\{ "content": "{"foo": "bar", "baz": "qux"}" }
;
const lambda_response = try lambda_request(allocator, request, 5);
defer deinit();
defer allocator.free(lambda_response);
try std.testing.expectEqualStrings(expected_response, lambda_response);
}