I don’t get it, how would a database container run your unit tests? And unless you know some secret option to stop the database after, say, it is idle for a few seconds, it will continue running.
The purpose is to test database dependent code by spinning up a real database and run your code against that.
For me the value of podman is how easily it works without root. Just install and run, no need for sudo or adding myself to docker group.
I use it for testing and dev work, not for running any services.
It’s the same picture.
The left axis is total number of ratings of each type (Garbage, Bronze, Silver, Gold, Platinum) in a given month (not per app). For example for month 2016-07
there were
"Garbage" => 22
"Bronze" => 14
"Silver" => 13
"Gold" => 55
"Platinum" => 61
On right side is the average rating. So if I assign values to each rating:
"Garbage" => 1
"Bronze" => 2
"Silver" => 3
"Gold" => 4
"Platinum" => 5
I can get an average rating, which will be between 1 to 5.
((22*1) + (14*2) + (13*3) + (55*4) + (61*5)) / (22 + 14 + 13 + 55 + 61)
~= 3.721
No… too hard.
I didn’t know the answer either, but usually you can compose solution from solutions of smaller problems.
solution(0): There are no disks. Nothing to do. solution(n): Let’s see if I can use solution(n-1) here. I’ll use solution(n-1) to move all but last disk A->B, just need to rename the pins. Then move the largest disk A->C. Then use solution(n-1) to move disks B->C by renaming the pins. There we go, we have a stack based solution running in exponential time.
It’s one of the easiest problem in algorithm design, but running the solution by hand would give you a PTSD.
Replacing “Programmers:” with “Program:” is more accurate.
Tower of Hanoi is actually easy to write program for. Executing it on the other hand…
Technically, containers always run in Linux. (Even on windows/OS X; on those platforms docker runs a lightweight Linux VM that then runs your containers.)
And I wasn’t even using Docker.
How I lost a Postgres database:
Just did some basic testing on broadcast addresses using socat, broadcast is not working at all with /32 addresses. With /24 addresses, broadcast only reaches nodes that share a subnet. Nodes that don’t share the subnet aren’t reachable by broadcast even when they’re reachable via unicast.
Edit1: Did more testing, it seems like broadcast traffic ignores routing tables.
On 192.168.0.2, I am running socat -u udp-recv:8000,reuseaddr -
to print UDP messages.
Case 1: add 192.168.0.1/24
# ip addr add 192.168.0.1/24 dev eth0
# # Testing unicast
# socat - udp-sendto:192.168.0.2:8000 <<< "Message"
# # Worked
# socat - udp-sendto:192.168.0.255:8000,broadcast <<< "Message"
# # Worked
Case 2: Same as above but delete 192.168.0.0/24 route
# ip addr add 192.168.0.1/24 dev eth0
# ip route del 192.168.0.0/24 dev eth0
# # Testing unicast
# socat - udp-sendto:192.168.0.2:8000 <<< "Message"
2024/02/13 22:00:23 socat[90844] E sendto(5, 0x5d3cdaa2b000, 8, 0, AF=2 192.168.0.2:8000, 16): Network is unreachable
# # Testing broadcast
# socat - udp-sendto:192.168.0.255:8000,broadcast <<< "Message"
# # Worked
Here is a trick that has been tried and tested over the years: Install another distro, and use that to install Arch. This way, you can rely on an already working linux distro till your Arch install works the way you want.
I was thinking along the lines of
Plenty of libraries can build the XML using structs/classes. e.g. with serde:
//Data type for row
#[derive(serde::Serialize)]
pub struct Foo {
pub status: String,
pub name: String,
}
//Example row
let ent = Foo {
status: "paid".into(),
name: "bob".into(),
}
//Example execution
sqlx::query(&serde_xml_rs::to_string(&InsertStmt{
table: "foo".into(),
value: &ent,
})?).execute(&conn)?;
Or with jackson-dataformat-xml:
//Data type for row
public class Foo {
public string status;
public string name;
}
//Example row
Foo ent = new Foo();
foo.status = "paid";
foo.value = "bob";
//Example execution
XmlMapper xmlMapper = new XmlMapper();
String xml = xmlMapper.writeValueAsString(new InsertStmt("foo", ent));
try (Statement stmt = conn.createStatement()) {
stmt.executeUpdate(xml)
}
I don’t do JS (yet) but maybe JSX could also do similar things with XML queries.
No more matching $1, $2, … (or ?
for mysql) with individual columns, I could dump entire structs/objects into a query and it would work.
Better than parameterized queries. Yes, we have stuff like query("INSERT INTO table(status, name) VALUES ($1, $2);").bind(ent.status).bind(ent.name).execute...
, but that’s kind of awful isn’t it?
With XML queries, we could use any of the XML libraries we have to create and manipulate XML queries without risking ‘XML injection’. e.g we could convert ordinary structs/classes into column values automatically without having to use any ORM.
I actually like this. This would allow reuse of all the infrastructure we have around XML. No more SQL injection and dealing with query parameters? Sign me up!
We can say default is and
and add an Or
node for or
. Similar to SoP notation, you only write +
.
I am glad that atleast it ends there. It could have been worse.
Thanks man, my brain was short-circuited on Testcontainers so I couldn’t write better. Also I am stealing the title.