When using node.js we have npx - a tool that makes it easy for users to install and manage applications (especially CLI tools) rather than libraries. For Python there is pipx. Is there a tool for OCaml that offers the same functionality?
pipx run "$APP" --example foo" install & update & run all-in-one
Apps are installed into isolated environments so that they do not step on each other's toes. (e.g. incompatible dependency requirements)
I know there is one general-purpose option - Docker, but is there anything tailored to OCaml?
Edit: the main reason I dislike Docker is that it alters my view of the filesystem. A CLI tool might accept paths via the arguments, the environment and config files and then open them. Reading relative to CWD is also common. If a CLI tool is distributed via Docker, the user has to be aware of the altered filesystem view, which adds cognitive overhead.
If you browse the list of OPAM packages, you will see not only libraries, but also applications. A few examples from a quick perusal:
dune
dumpast
utop
xe
I have Linux Droplet on Digital Ocean, and I want to run on it some services – like SpringbootWeb and React.js.
Clearly I need to run the servers all the time, without being depends
on the terminal on/off (I’m using Putty) and I am planning to do it ,
by using nohup.
I saw other methods like those
In spring boot (See 3. Installing Spring Boot Applications) and in npm.
But I prefer for now use nohup since it’s easier and simpler.
I there is problem with that approach and it considered “bad practice” for production ?
(And if does, what considered a good practice ?)
Edit
Now seeing that nohup not saving react running after closing Putty-console
found also this idea for deploying React on nginx. (Digital Ocean run nginx)
There's nothing wrong with it, but you would still need to create some sort of init script to start your app on boot and stop it on shutdown.
So on a Linux system you would typically want to use systemd unit files for this, and have the init system handle the lifecycle of your server application. The reference guide mentions it here, or refer to this as a more complete example.
Can nix be used in a continuous-delivery workflow?
We're using semaphore as our continuous integration service, and now I'm looking into building packages upon a successful build. For this I'm considering using nix.
I don't know what would be the right way of setting up a continuous delivery pipeline with this package manager. It seems that such an automated process would involve:
Making a branch of the nixpkgs repository (in the CI server).
Updating the rev field of fetchFromGithub.
(automatically) submitting a pull-request.
But I don't know if this makes sense, and also I'm concerned that the continuous-delivery process involved a manual step (having an human aproving the pull-request).
Can nix be used in a continuous-delivery workflow?
Yes. It's typically done with Hydra, a CI system built with Nix. But, it may be possible to do this with Semaphore.
Semaphore CI provides build environments that are language specific, but... it's running Ubuntu, so theoretically you can do something like this:
Install Nix as if it were a dependency. See this article.
Add your Nix package, which I suppose you can do with Git. You don't really need to clone Nixpkgs.
Use nix-build to build your package. This will create a result symbolic link to the build output.
Deploy using git-deploy.
If you do something like this with your package you can call it directly from nix-build because you won't have to provide the package dependencies as arguments:
{ pkgs ? import <nixpkgs> {} }:
let
stdenv = pkgs.stdenv;
...
in
stdenv.mkDerivation {
..
}
Optimization
Installing Nix for every build is wasteful, but perhaps you can cache the Nix store. See this article.
I have the following boxes:
a) A Windows box with Eclipse CDT,
b) A Linux box, accessible for me only via SSH.
Both the compiler and the hardware required to build and run my project is only on machine B.
I'd like to work "transparently" from a Windows box on that project using Eclipse CDT and be able to build, run and debug the project remotely from within the IDE.
How do I set up that:
The building will work? Any simpler solutions than writing a local makefile which would rsync the project and then call a remote makefile to initiate the actual build? Does Eclipse managed build have a feature for that?
The debugging will work?
Preferably - the Eclipse CDT code indexing will work? Do I have to copy all required header files from machine B to machine A and add them to include path manually?
Try the Remote System Explorer (RSE). It's a set of plug-ins to do exactly what you want.
RSE may already be included in your current Eclipse installation. To check in Eclipse Indigo go to Window > Open Perspective > Other... and choose Remote System Explorer from the Open Perspective dialog to open the RSE perspective.
To create an SSH remote project from the RSE perspective in Eclipse:
Define a new connection and choose SSH Only from the Select Remote System Type screen in the New Connection dialog.
Enter the connection information then choose Finish.
Connect to the new host. (Assumes SSH keys are already setup.)
Once connected, drill down into the host's Sftp Files, choose a folder and select Create Remote Project from the item's context menu. (Wait as the remote project is created.)
If done correctly, there should now be a new remote project accessible from the Project Explorer and other perspectives within eclipse. With the SSH connection set-up correctly passwords can be made an optional part of the normal SSH authentication process. A remote project with Eclipse via SSH is now created.
The very simplest way would be to run Eclipse CDT on the Linux Box and use either X11-Forwarding or remote desktop software such as VNC.
This, of course, is only possible when you Eclipse is present on the Linux box and your network connection to the box is sufficiently fast.
The advantage is that, due to everything being local, you won't have synchronization issues, and you don't get any awkward cross-platform issues.
If you have no eclipse on the box, you could thinking of sharing your linux working directory via SMB (or SSHFS) and access it from your windows machine, but that would require quite some setup.
Both would be better than having two copies, especially when it's cross-platform.
I'm in the same spot myself (or was), FWIW I ended up checking out to a samba share on the Linux host and editing that share locally on the Windows machine with notepad++, then I compiled on the Linux box via PuTTY. (We weren't allowed to update the ten y/o versions of the editors on the Linux host and it didn't have Java, so I gave up on X11 forwarding)
Now... I run modern Linux in a VM on my Windows host, add all the tools I want (e.g. CDT) to the VM and then I checkout and build in a chroot jail that closely resembles the RTE.
It's a clunky solution but I thought I'd throw it in to the mix.
My solution is similar to the SAMBA one except using sshfs. Mount my remote server with sshfs, open my makefile project on the remote machine. Go from there.
It seems I can run a GUI frontend to mercurial this way as well.
Building my remote code is as simple as: ssh address remote_make_command
I am looking for a decent way to debug though. Possibly via gdbserver?
I tried ssh -X but it was unbearably slow.
I also tried RSE, but it didn't even support building the project with a Makefile (I'm being told that this has changed since I posted my answer, but I haven't tried that out)
I read that NX is faster than X11 forwarding, but I couldn't get it to work.
Finally, I found out that my server supports X2Go (the link has install instructions if yours does not). Now I only had to:
download and unpack Eclipse on the server,
install X2Go on my local machine (sudo apt-get install x2goclient on Ubuntu),
configure the connection (host, auto-login with ssh key, choose to run Eclipse).
Everything is just as if I was working on a local machine, including building, debugging, and code indexing. And there are no noticeable lags.
I had the same problem 2 years ago and I solved it in the following way:
1) I build my projects with makefiles, not managed by eclipse
2) I use a SAMBA connection to edit the files inside Eclipse
3) Building the project:
Eclipse calles a "local" make with a makefile which opens a SSH connection
to the Linux Host. On the SSH command line you can give parameters which
are executed on the Linux host. I use for that parameter a makeit.sh shell script
which call the "real" make on the linux host.
The different targets for building you can give also by parameters from
the local makefile --> makeit.sh --> makefile on linux host.
The way I solved that one was:
For windows:
Export the 'workspace' directory from the Linux machine using samba.
Mount it locally in windows.
Run Eclipse, using the mounted 'workspace' directory as the eclipse workspace.
Import the project you want and work on it.
For Linux:
Mount the 'workspace' directory using sshfs
Run Eclipse.
Run Eclipse, using the mounted 'workspace' directory as the eclipse workspace.
Import the project you want and work on it.
In both cases you can either build and run through Eclipse, or build on the remote machine via ssh.
For this case you can use ptp eclipse https://eclipse.org/ptp/ for source browsing and building.
You can use this pluging to debug your application
http://marketplace.eclipse.org/content/direct-remote-c-debugging
How to edit in Eclipse locally, but use a git-based script I wrote (sync_git_repo_from_pc1_to_pc2.sh) to synchronize and build remotely
The script I wrote to do this is sync_git_repo_from_pc1_to_pc2.sh.
Readme: README_git-sync_repo_from_pc1_to_pc2.md
Update: see also this alternative/competitor: GitSync:
How to use Sublime over SSH
https://github.com/jachin/GitSync
This answer currently only applies to using two Linux computers [or maybe works on Mac too?--untested on Mac] (syncing from one to the other) because I wrote this synchronization script in bash. It is simply a wrapper around git, however, so feel free to take it and convert it into a cross-platform Python solution or something if you wish
This doesn't directly answer the OP's question, but it is so close I guarantee it will answer many other peoples' question who land on this page (mine included, actually, as I came here first before writing my own solution), so I'm posting it here anyway.
I want to:
develop code using a powerful IDE like Eclipse on a light-weight Linux computer, then
build that code via ssh on a different, more powerful Linux computer (from the command-line, NOT from inside Eclipse)
Let's call the first computer where I write the code "PC1" (Personal Computer 1), and the 2nd computer where I build the code "PC2". I need a tool to easily synchronize from PC1 to PC2. I tried rsync, but it was insanely slow for large repos and took tons of bandwidth and data.
So, how do I do it? What workflow should I use? If you have this question too, here's the workflow that I decided upon. I wrote a bash script to automate the process by using git to automatically push changes from PC1 to PC2 via a remote repository, such as github. So far it works very well and I'm very pleased with it. It is far far far faster than rsync, more trustworthy in my opinion because each PC maintains a functional git repo, and uses far less bandwidth to do the whole sync, so it's easily doable over a cell phone hot spot without using tons of your data.
Setup:
Install the script on PC1 (this solution assumes ~/bin is in your $PATH):
git clone https://github.com/ElectricRCAircraftGuy/eRCaGuy_dotfiles.git
cd eRCaGuy_dotfiles/useful_scripts
mkdir -p ~/bin
ln -s "${PWD}/sync_git_repo_from_pc1_to_pc2.sh" ~/bin/sync_git_repo_from_pc1_to_pc2
cd ..
cp -i .sync_git_repo ~/.sync_git_repo
Now edit the "~/.sync_git_repo" file you just copied above, and update its parameters to fit your case. Here are the parameters it contains:
# The git repo root directory on PC2 where you are syncing your files TO; this dir must *already exist*
# and you must have *already `git clone`d* a copy of your git repo into it!
# - Do NOT use variables such as `$HOME`. Be explicit instead. This is because the variable expansion will
# happen on the local machine when what we need is the variable expansion from the remote machine. Being
# explicit instead just avoids this problem.
PC2_GIT_REPO_TARGET_DIR="/home/gabriel/dev/eRCaGuy_dotfiles" # explicitly type this out; don't use variables
PC2_SSH_USERNAME="my_username" # explicitly type this out; don't use variables
PC2_SSH_HOST="my_hostname" # explicitly type this out; don't use variables
Git clone your repo you want to sync on both PC1 and PC2.
Ensure your ssh keys are all set up to be able to push and pull to the remote repo from both PC1 and PC2. Here's some helpful links:
https://help.github.com/en/github/authenticating-to-github/connecting-to-github-with-ssh
https://help.github.com/en/github/authenticating-to-github/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent
Ensure your ssh keys are all set up to ssh from PC1 to PC2.
Now cd into any directory within the git repo on PC1, and run:
sync_git_repo_from_pc1_to_pc2
That's it! About 30 seconds later everything will be magically synced from PC1 to PC2, and it will be printing output the whole time to tell you what it's doing and where it's doing it on your disk and on which computer. It's safe too, because it doesn't overwrite or delete anything that is uncommitted. It backs it up first instead! Read more below for how that works.
Here's the process this script uses (ie: what it's actually doing)
From PC1: It checks to see if any uncommitted changes are on PC1. If so, it commits them to a temporary commit on the current branch. It then force pushes them to a remote SYNC branch. Then it uncommits its temporary commit it just did on the local branch, then it puts the local git repo back to exactly how it was by staging any files that were previously staged at the time you called the script. Next, it rsyncs a copy of the script over to PC2, and does an ssh call to tell PC2 to run the script with a special option to just do PC2 stuff.
Here's what PC2 does: it cds into the repo, and checks to see if any local uncommitted changes exist. If so, it creates a new backup branch forked off of the current branch (sample name: my_branch_SYNC_BAK_20200220-0028hrs-15sec <-- notice that's YYYYMMDD-HHMMhrs--SSsec), and commits any uncommitted changes to that branch with a commit message such as DO BACKUP OF ALL UNCOMMITTED CHANGES ON PC2 (TARGET PC/BUILD MACHINE). Now, it checks out the SYNC branch, pulling it from the remote repository if it is not already on the local machine. Then, it fetches the latest changes on the remote repository, and does a hard reset to force the local SYNC repository to match the remote SYNC repository. You might call this a "hard pull". It is safe, however, because we already backed up any uncommitted changes we had locally on PC2, so nothing is lost!
That's it! You now have produced a perfect copy from PC1 to PC2 without even having to ensure clean working directories, as the script handled all of the automatic committing and stuff for you! It is fast and works very well on huge repositories. Now you have an easy mechanism to use any IDE of your choice on one machine while building or testing on another machine, easily, over a wifi hot spot from your cell phone if needed, even if the repository is dozens of gigabytes and you are time and resource-constrained.
Resources:
The whole project: https://github.com/ElectricRCAircraftGuy/eRCaGuy_dotfiles
See tons more links and references in the source code itself within this project.
How to do a "hard pull", as I call it: How do I force "git pull" to overwrite local files?
Related:
git repository sync between computers, when moving around?
If it's possible, I'm interested in being able to embed a PostgreSQL database, similar to sqllite. I've read that it's not possible. I'm no database expert though, so I want to hear from you.
Essentially I want PostgreSQL without all the configuration and installation. If it's possible, tell me how.
Run postgresql in a background process.
Start a separate thread in your application that would start a postgresql server in local mode either by binding it to localhost with some random free port or by using sockets (does windows support sockets?). That should be fairly easy, something like:
system("C:\Program Files\MyApplication\pgsql\postgres.exe -D C:\Documents and Settings\User\Local Settings\MyApplication\database -h 127.0.0.1 -p 12345");
and then just connect to 127.0.0.1:12345.
When your application quits, you can always send a SIGTERM to your thread and then wait a few seconds for postgresql to quit (ie join the thread).
PS: You can also use pg_ctl to control your "embedded" database, even without threads, just do a "pg_ctl start" (with appropriate options) when starting the application and "pg_ctl stop" when quitting it.
You cannot embed it, nor should you try.
For embedding you should use sqlite as you mentioned or firebird rdbms.
Unless you do a major rewrite of code, it is not possible to run Postgres "embedded". Either run it as a separate process or use something else. SQLite is an excellent choice. But there are others. MySQL has an embedded version. See it at http://mysql.com/oem/. Also several java choices, and Mac has Core Data you can write too. Hell, you can even use FoxPro. What OS you on and what services you need from the database?
You can't embed it as a in process type thing like sqlite etc, but you can easily embed it into your application setup using Inno setup at http://www.innosetup.org. Search their mailing list archive and you will find someone did most of the work for you and all you have to to is grab the zipped distro and you can easily have postgresql installed when the user installs your app. You can then use the pg_hba.conf file to restrict the server to local host only. Not a true embedded DB, but it would work.
PostgreSQL is intended to run as a stand-alone server; it's probably possible to embed it if you hack at it hard and long enough, but it would be much easier to just run it as intended in a separate process.
HSQLDB (http://hsqldb.org/) is another db which is easily embedded. Requires Java, but is an excellent and often-used choice for Java applications.
Anyone tried on Mac OS X:
http://pagesperso-orange.fr/bruno.gaufier/xhtml/prod_postgresql.xhtml
http://www.macosxguru.net/article.php?story=20041119135924825
(Of course sqlite would be my embedded db of choice as well)
Well, I know this is a very very very old post, but if anyone has nowadays this question, I would refer to:
You can use containers running Postgres. Here's a post that could be helpful, doing something along this line using R:
https://rsangole.netlify.app/post/2021/08/07/docker-based-rstudio-postgres/?utm_source=pocket_mylist
Take a look at duckdb https://duckdb.org/docs/installation/ It is relatively new and still needs to mature. But it works pretty much like an embedded database ("In-process, serverless"), with bindings for several languages (Python, R, Java, ...)